re: imperialistic countries
No matter how strong their military they could never have controlled such a vast and nationalistic area.
Maybe. Remember, a lot of the Soviet Union was anything but Russian as far as nationalism goes, and nationalism didn't count for much during the Russian Civil War. It's also possible that a successful German invasion of the U.S.S.R. would have involved a simple switching of tyrants for most of the population.
I don't think most people know how close we came to having much of the world controlled either by the Soviet Union or the Third Reich.