A lot of people are taking about Germany just rolling in during the Russian Civil war so as to keep Russia under German conrtol, but would there really be THAT much of a civil war? As far as I remember (This is from my semi-forgotten school days) the Whites were only supported by the Allied armies trying to keep Russia in the war, after the war ended and the Allies went home the White support collapsed Very quickly. If the US keeps strict neutrality then Britain would be far more focused on the Western Front and keeping the Germans as far away from Britain as possible to be able to send troops galavanting of to Archangel.
And since the Germans sent Lenin anyways, I'd think they wouldn't be worrying too much about Russia. They'd have the vassel Eastern European states and set up some new nationalistic ones ie Southern Russia, The Caucases, Crimea as buffers incase the Russians even think about trying to start something. And since the Russian army wouldn't likely be a threat to the now even stronger German one, I think the Germans would just leave the Russians to whatever mess they get themselves into. The only problem would be if Trotskey and his supporters win and try starting some revolutions in East Europe. In which case we'd also see a weaker Russian SFSR as the revolution would still be Idealist rather than the pragmatism of Stalin.
I think Germany would prop up Austria-Hungary so as to keep tabs on the Slavic balkin states who might want to make trouble as revenge for the war. Maybe even some sevre Austrian reprisals against Serbia/Slavs. Either another pogrom or an earlier Holocaust. The Balkans I think would become more subdued as both the Austrian's and the Ottomans carve it up and then sit tightly on the lid.
France would get massive reperations. Possibly lose a load of it's colonies (at leas the important wealthy ones) Alsace-Lorraine etc. I'm not too sure if they'd be so harsh on the army etc. Seeing themselves as now top-dog of Europe they might be arrogant enough to leave it at a reasonable size. France might descend to a new revolution against the seemingly weak government and hopeless defeat. It could either be a Left or Right wing depending on who gets the blame the politicians or the military, respectively. I dont think it'd be communist, but rather a slightly more extreme French Socialism.
Britain will stay Britain, aloof and seperate from the continent as always. The Royal Navy will protect them from anything severe apart from some neutrality treaties and probably favourable trade concessions to Germany. The opening of a few previously British-only markets to the Germans.
Oh! Italy might actually get it harder than France for breaking their treaty. With reperations and loss of colonies and shipping etc. Possibly a lot of territory to Austria. The loss of their few colonies to Germany and maybe cut backs in their fleet. The possibility of a German Mediterranian port...Altough that's a bit weird.
The US might be sitting there worrying slightly about this now powerful Germany and wondering if it should have gotten involved. Maybe a few feelers out to see if a League Of Nations-esque entity can be set up. But economic problems back home might cut that short.
Japan would be able to grab the territories it wanted anyways and so would stay relativly happy and apparently forgotten. The only trouble might be with new German colonies in China/SE Asia. Which might mean a still-Allied Japan, altough it could go either way.
But anyways for a post that was meant to be about Mitteleuropa, back to a question in the OP, I think the New German Empire would be economically powerful but not elightened. I think the enlightenment of the 20's/30's will occur in Britain or the US as the Intellectuals flee the overpowering Germans and the anarchy in France. A second Scottish Enlightenment might happen ^^. As for what would occur later. The tensions might rise if the global collapse still happens, tenisons will rise up possibly in Italy, as the new extreme facist state out for revenge, coupled with the revolutionary France and nationalists in Eastern Europe, And maybe Japan in Asia striking at the German colonies. It'd be a bit of a hodge podge of Allies but it might work if the Germans are complacent and exhausted after the years of war followed by the Flu epidemic and the economic downturn. And if the word of the ethnic cleansing of the Balkans/East Europe gets out it might finally rouse the US out of it's neutrality albeit not the economic powerhouse it could have been but still strong. Could turn out with France and Italy as the power duo of Europe with a cold war with a more NW/SE split, a more Balkanised Eastern Europe, with possible Yugoslav analogues happening. And a strong but not ultimatly dominant States.Maybe vying for Power with Britain, Japan, France, Italy in the world after the Second Great War.
I'll shut up now. Sorry tangents ¬_¬ Also sorry for the wall of text on a basically-first post =/