Starvation can be fast or slow. If "fast", that's still a year or so, during which the riots will take place every day, everywhere. That's an awful lot of troops tied down, widespread destruction, production disrupted, and casualties for the German forces.
Wha..? How? When did anything like this occur in OTL that significantly impacted on Germany's abilities? Sure there were uprising in the ghettoes in Poland, but why would the rest of European Russia and the Caucasus present a different situation to what happened in Poland, the Ukraine and the Baltics & Belarus in OTL from 1941 onwards? Sure there will be partisans and riots and so forth, but it isn't like those things weren't be handled from 1941-1943 in the occupied areas already - and that too with an
active front line. If there is no front line against an organized Soviet Red Army as must be assumed if Barbarossa is to be successful then all those troops that were previously too busy fighting at the front will now be free to carry out garrison duties. Anything less than a total capitulation (formal or effective capitulation) of the Red Army and Soviet Union cannot be considered a "successful" Barbarossa, because otherwise it would mean that there is the potential for the Red Army to counterattack as it did in OTL.
_Then_ things will cool down, but there will still be problems with production due to the extensive destruction and the shortage of workers.
But why would it be any different than in the occupied areas of the USSR from OTL from 1941-1943? During that time, millions of workers were actually sent (or volunteered) to go to Germany to make up the work shortage there and in OTL the occupied areas throughout Europe raised capital, part of which went towards the occupation costs.
If starvation is slow, then garrisons can be cut back – but that level of garrisoning, albeit reduced, will have to stay in place for a decade or so.
Right, but your thinking in terms of decades, but that's skipping a few steps. For any garrison to remain for a decade, it would require undisputed mastery of Europe, which in turn would require Germany to win the war, so they would need to transfer some of the troops to other areas such as France and North Africa (I doubt any Barbarossa can be successful after mid 1942 if everything else essentially remained the same in the TL) in order to ensure that the Allies have virtually no way of attacking the Continent.
As to the minor Axis allies' slices, of course the governments will ask for their own state's official slice. What I'm saying is that the local troops always took their own private unofficial slice too. In occupied France, that tended to amount to 15%. That applies to consumer goods alright, not to ammunition crates; but "consumer goods" definitely includes things like foodstuffs and coal. it weas tolerable to the Germans insofar as that went to the welfare of their own soldiers and families.
Except the reason why Romania and Hungary even sent troops for Barbarossa in the first place was to curry favour with Hitler in hopes of changing (for Romania) or keeping (for Hungary) the situation that existed in northern Transylvania. Romania also got territory from the Ukraine (Transnistria), but the Romanian and Hungarian soldiers went much farther than would have been required if they were simply there to obtain territory and control for their respective governments. In fact, Romania so wanted to curry Hitler's favour that it apparently sent more soldiers to die over there than even Italy - amounting to some 800,000 mobilized in total apparently. This competition to gain favour with Hitler wouldn't stop with a successful Barbarossa as long as there is still something either country could do that might swing Hitler's opinion.
And whether local troops took their own unofficial slice, why would Hitler even care? Whether the local troops taking an unofficial cut were German or Romanian, it wouldn't make a difference because the "cut" was unofficial anyway and something that wouldn't be approved of if it was brought to the attention of the tops of the chain of command. In northern France, there were only German troops and as you said, they still took a cut which amounted to 15%. It was only tolerable because it was probably too widespread and of not enough consequence for anything to be done about it. The same would apply elsewhere and since every Romanian or Hungarian soldier that remained in a support role for the temporary occupation of the USSR (until the Axis get an armistice with Britain and maybe the USA or at least until the threat of Allied invasion of Europe is effectively nil) would free up a German soldier for continued operation towards that end (ensuring victory in Europe), there is no reason why such unofficial cuts wouldn't be tolerated from Hungarian or Romanian troops as well since the benefits (ensuring victory in Europe) would be as great, if not greater than the costs (losing some coal and food, some of which would probably have gone to Romania and Hungary anyway, since whether or not their soldiers are in the USSR they still have to eat).
The whole of North Africa was fully in Allied hands by april 1943, actually. However, if the Germans are 100% focused on the USSR – which for me is a requisite if we want a victory by the end of 1942, otherwise we have OTL to show what will happen – they don't help the Italians out down there. In that case by mid 1942 if not earlier North Africa will be Spanish, Vichy French, and British.
How? What happens to change the situation in North Africa by mid 1942? As you yourself said earlier, it is impossible to expect that Germany would remove 100% of its forces from the USSR after victory and likewise it would be impossible to expect that they would do the opposite and remove 100% of their forces from elsewhere in order to obtain victory in the USSR. They had 150 divisions in the USSR (plus the armies of their puppets from Italy, Hungary, Romania, Slovakia and Croatia along with volunteers from Spain and elsewhere in Europe). In OTL the German losses from May 1941 to May 1942 were about 600,000 (Barbarossa and North Africa being the active fronts at the time). Unless changes are made in the TL from 1938 like Rhysz attempted then any changes made to Barbarossa will probably require Germany taking Moscow by late 1941/early 1942 and moving on to the A-A line by mid 1942. Otherwise they are going to end up losing momentum as in OTL and giving the Red Army time to counter and extending any possible victory into 1943...but which would probably require something like what was attempted at the Caucasus and Stalingrad (plus given Hitler's ego, he is still likely to want to capture Stalingrad and so set his own generals up for failure if the Soviets can turn Stalingrad into a focus point as happened in OTL). And if Barbarossa isn't dealt with by 1943 then North Africa is already in Allied hands and so is part of Italy, which means that Germany would get bogged down as in OTL fighting in Italy and probably not have enough momentum to take the initiative in the USSR especially as by 1943, we have to take into account the effect of continued lend-lease aid to Germany and the fact that Germany would not have been able to spend enough resources to counter the bombing threat from the USAF and RAF which would continue to drain at Germany's potential to actually make war and thus obtain victory in Barbarossa by 1943 in the first place.
Also in OTL, from May 1942 to May 1944 German losses amounted to 2.5 million, of which a significant majority came from the eastern front. Even if we assume 60% of that figure is from the eastern front that would be 1.5 million soldiers. If Germany lost an extra 400,000 by May 1942 in winning Barbarossa, the losses garnered afterwards from riots by lightly armed peasants, etc is unlikely to amount to 1 million soldiers between 1942 and 1944. Less soldiers dead would mean more left alive to garrison and to be used elsewhere.
By May 1943 in OTL Germany had an active strength of 9.5 million and a total loss of 1.7 million (for a total mobilization of 11.2 million). Butterfly away the haemorrhage that was the active eastern front by mid 1942 and Germany might have an extra 300-400,000 soldiers left alive for a total strength of 9.8 - 9.9 million. With extra soldiers to throw at North Africa (even if the Allies land which is still less likely with any Barbarossa victory as it would not be assured that Vichy French forces would not put up resistance as they successfully did in repelling an Allied attempt at Dakar - and now if Germany was successful in Russia, what reason would the Vichy French forces have for believing that the Allies could still overcome Germany?).
We're looking at a few years, you know. So keeping the friendly Italians and Romanians etc. losing weight _is_ going to be a problem. And in a perspective of say 3 years, you need to fill those granaries every year. Actually you need to protect the countryside from the wandering hordes of near-starved, desperate city dwellers who will be out to dig out the next year's sowings, to assault the local miller's cart and the isolated farm's pigsty and such like.
But no more of a problem than OTL and with the added bonus that they now have control over more granaries, etc than in OTL and without the expense of an active and massive eastern front using up resources like a sponge. And since they (the friendly Italians and Romanians in the rest of Axis Europe) would have and were fed in OTL and didn't die of starvation why would it be any different in TTL when they have control over more foodstuff?
As to the general's comment, it was heard all right. The Germans did not treat the Ukrainans kindly – that's why I always laugh when I read the proposed PODs of recruiting millions of happy Ukrainans to fight the Soviets. But neither did the Germans carry out the whole GPO policies or the even more nightmarish ideas some of the Nazi leadership floated at times. They did kill the Jews and most of the first batches of POWs, and they did slowly starve most the city dwellers. But they had to feed workers serving their war machine and above all they had to let the peasants eat insofar as they provided them with their quotas, since they were the ones closest to the source. The GPO provided that the whole Ostheer should be entirely fed at the expense of the occupied territory by the third year of the war (in the East), and that objective was never achieved, even though in 1943 the Germans were still controlling most of the areas from where most of the food came.
But in 1943 with a successful Barbarossa they would be controlling more land with less troops dead. Let's say that out of the 3.5 million sent into Barbarossa as 150 divisions, that Germany lost 1 million. Now the European USSR is 5 or 6 times the size of France but a substantial portion of it is more northerly than France (and more about the same latitude as Norway). In addition the European USSR is much less densely populated than France (and would be more so with refugees who flee east). France had 50 divisions in occupation according to an earlier post and Norway had 12 divisions in occupation (of which about 60% or 7 divisions were actually used to garrison Norway, while the other 5 were used to support Barbarossa). Norway though is 60% of the size of France but has a population of about 7-8% that of France. However the number of German divisions in Norway was 24% of what was in France (not 60% to conform with the territory) and about 14% of what was in France if only those actually garrisoning the country are considered. So the USSR will not require 5-6 times the numbers required for France and I suspect that given Germany could still mobilize more troops between 1942 and 1943 in OTL, that it could leave behind 60 divisions in occupation of the northern and central portions of the European USSR and 25 divisions in occupation of southern European USSR (especially the Caucasus). If they lost 1 million out of the original 3.5 million and thus lost about a third of the 150 divisions that leaves 85 divisions in the USSR and 25 divisions free to go elsewhere (plus the 200,000 Italian soldiers who would be free to go to Italy and North Africa). Those 25 divisions in the Caucasus could then provide perhaps 10-15 divisions to carry out an expedition into Iran which would was being occupied by the Soviets (now defeated) and the British (who had only 2 divisions and 3 brigades in that country). And since the British force in Iraq and in Syria and Lebanon were of similar sizes, the most that the British could probably draw into Iran from the rest of their middle east forces would be probably 6-7 divisions (apart from Palestine/Transjordan and Egypt - which would be robbing Peter to pay Paul). The British could draw soldiers from India directly, but that may impact on their efforts against the Japanese in India and Burma...
Throw in the soldiers raised between 1942 and 1943 from OTL then Germany could have an extra 400,000 to send to help garrison the USSR and to go to northern France and North Africa.