a few quick observations....
to win a war against the Soviet Union the Germans have to use what worked for them in the Great War...
1. a large allied force (Austrians last time, if they play their cards better, the Eastern Europeans this time). The Poles fought a major war against the Soviets in 1919-1921 and won a defensive victory and achieved survival. That the Poles started the war to grab territory is important as well. Even if second rate in terms of equipment to the Germans, the Poles, Balts and other Eastern Europeans can absorb casualties and stretch out the front.
2. Prepare for the logistical demands of this campaign, which are indeed daunting and huge. Creveld goes into depth on how the Germans failed to do that in "Supplying War" The answer is not more trucks. The answer is spending resources on a better rail system with more slack in Germany, and devoting more men and resources to fixing the Soviet railways as they are overrun.
3. Know when to stop and dig in for the winter and or spring thaw
4. Fight to achieve a satisfactory victory. Conquering Russia isn't possible. Stripping away Soviet territory (trying for Brest Litovsk round 2 in other words) was in the Great War and might be here.
5. Unity of command ... someone running the front who is not the head of state with other demands on his time. Improves coordination all across the board. The 3 principal German army groups were bad at coordinating their actions unless directed to do so by the Fuhrer. So were the air fleets assigned to each one. Often the Germans robbed peter to pay paul during the campaign even when things were going well. Unit of command would reduce that kind of inefficiency.
To name just some things that went well for the Germans that do not require the Red Army to be the Imperial Russian Army
Regarding the Japanese... while a highly professional force and fairly large in 1936, the entire Japanese Army in 1937 only had 300,000 men and 17 divisions only part of which are in Manchuria. It lacks the manpower and formations to take on the Soviets in that era with hope of success. It needs at least 60 divisions, and least half for the operation for any hope of a successful Siberian adventure. As to equipment, while Japanese tanks aren't very good in 1936, neither are Soviet tanks. The BTs and T26s have some substantial issues, as of course do the Japanese tanks (type 97s). Point is however the Type 97 isn't available yet either. The Japanese have similar lack of depth in army aviation and while the IJN is a marvelous instrument in 1936 and would easily wipe out any Soviet ships that braved leaving port, it cannot do much more than that. Although I suspect a strong enough naval support assigned to an assault or siege of Vladivostok might give the Japanese that ... if it can be cut off from reinforcement (difficult)
Also important, the Japanese were prepared to fight a defensive war against the Soviets in the 1930s, but had no ambitions until they expanded their army in fighting an offensive one.
Meanwhile back in Germany....
the preparations, both military and diplomatic, you need require Hitler not being himself, or him being dead. Munich was the last chance for Hitler to achieve what he wanted peacefully. After that, he promptly seized the rest of Czechslovakia and permanently alienated the West. You need the West to fail to make Poland security guarantees and an alliance for the Poles to see alliance with Germany as a better answer than OTL. As the Poles have spent 20 years waging an internal propaganda war against both the Soviets and Germans, this is not easy. It isn't impossible, but again very hard. Hitler being around would to my mind make it impossible.
The points about German economic weakness are well put and well documented in a number of works. Getting the West to help Germany or at least not hinder it requires the West to see the Soviets as a bigger threat than Nazi Germany. This too is hard. The cash problem is indeed an issue.
Regarding a heavy bomber force. We know based on World War II experience that to really hit a target hard you need at least 300 heavy bombers to do it with. The Germans couldn't manage that in the 1930s and would be hard pressed to do so without a bigger industrial base than they had available. Even then it takes multiple raids and you still don't actually destroy the target, only cripple its productivity.
It took the Western Allies until 1944 to routinely get 300 American heavy bombers over a German target, and 1943 for the British to do it, as well as a painful learning curve. Now no one knows this in the 1930s, but still it would be a serious mistake for the Luftwaffe to forgo that chance to build one of the best tactical air forces ever fielded to build a heavy bomber force that would be more expensive and harder to maintain.
That said, having at least a hundred or so heavy bombers would be helpful for all kinds of missions from hitting Moscow at night to maritime patrol missions. It would require sacrifices though, or greater depth.
Regarding the Soviet Army... "Ivans War", a book that looks at the Red Army in some detail in the prewar and early war years, makes a good point about the lack of professionalism and substitution of party orthodoxy and zeal over effectiveness. It took some embarrassing fumbling in the Soviet invasion of Poland and worse fumbling in Finland along with the shock of the French collapse to really convince Stalin and the Party that military effectiveness requires professionalism and professional military officers who are competent even if they lack the true communist spirit.
Without those events, the Red Army will have to learn on the job. If it fights the Japanese in the 1930s it gets that chance. Without it it has to learn fighting the Germans. While the Germans aren't the experienced and tactically / operationally proficient force in 1939 that they were in 1940-41 (with Operation Merita... invasion of Yugoslavia and Greece probably their high point in that respect), they are still a lot better than the Soviets are in OTL in 1939. Defeating the Poles, who had a large army and who fought very bravely even while going down in defeat was something the Soviets weren't able to do in 1921.
My own suggestion, if you want a two front war with the Soviets, look at 1941, and assume the Japanese did get their ass handed to them and did something to remedy some of their worst problems.