If the war is quickly won, the terms will likely be less punitive; possibly, there will not be any (successful) revolution in the first place. I was working under the assumption that the Eastern War would still be a drawn-out affair.
According to previous and ongoing discussions on the duration of the war, we may assume that the war would be significantly shorter than OTL, certainly not 4 years. How much shorter essentially depends on the role of UK, whether active belligerant on the Alliance's (especially if from the start) or friendly neutral. Personal estimations are in the range of 1-2 years, most of it to subdue Russia, indeed. Even in the worst scenario, I highly doubt Russia can stand more than a couple years, although.
Since it would be a total defeat, with huge loss of territory, a revolution is highly likely, proabaly successful in ending autocracy (Feb. 1917), not necessarily to put radical revolutionaries into power (Oct. 1917), that's subject to butterflies.
As it concerns peace terms, IMO the duration of the war essentially reflects in the degree of punitive viciousness reparations go into. No matter the duration, peace terms would be highly punitive as territories and colonies go. Russia gets a Brest-Litovsk deal, France loses the rest of Alsace-Lorraine, French Flanders, Italy's claims, large part or all of her colonial empire (how much depends on British colonial greed). That kind of punitive peace was Germany's war aim, and Italy would be quite greedy to feast on French booty.
Stalin was also presiding over a sovereign country that did not have massive debts (Lenin wrote them off unilaterally, a major reason for Soviet Russia going unrecognised for quite some time). As such, the Communist government also had an altogether different degree of control over the economy, something that I suspect the Germans would frown upon their "friendly" Russia assuming. And they cannot sell Baku oil or Ukrainian grain to finance the heavy equipment.
According to the Nazi precedent, it is not a given nor unplausible that Germany and her allies may fall into complacency and let a resurgent Russian nationalist leadership repudiate the debt. It is true that a Russia proper cannot rely on natural resources of Caucasus or Ukraine to finance the debt. They can exploit the resources of Siberia and Central Asia for that. But since they need to be developed, it is correct to assume TTL Russian industrialization will be somewhat slower and reduced than OTL. Likely still enough to rebuild Russia as a great power, although.
That depends; a glorious victory might give the monarchy the prestige it needs to remain in power.
Oh, I have no doubt that in a victorious German Empire the prestige of the monarchy will be boosted enough to establish it for the foreseeable future. But I have also severe doubts that it will remain the semi-autocratic compomise it was under Bismarck. I picture a democratization either/both before the war (a successful CP suggests a more politically wise pre-war leadership, if they gain British friendship for good, and that heavily suggest some form of democratization) and/or after it, as the mass parties claim full constitunalization and greater power share as the price of their loyalty during the war.
I do not visualize full British parliamentarism as necessary or likely, rather abolition of the Prussian unequal electoral system, and a government both responsible to the Reichstag and the Kaiser, with the latter keeping vast reserve powers in foreign and defense policy, legislative initiative for the Reichstag, but veto power for the Kaiser. A constitution rather similar to a monarchical French Fifth Republic.
France was democratic when they occupied the Ruhr. People in this time and age were much less squeamish abut such matters than is the case today.
And good for them. Pacifism is the senile illness of democracy.

