V rockets were NOT accurate at all. Putting a nuke in it would be handicapped for many reasons:
You would most likely miss the target. V rockets weren't designed to hit targets; they were designed to just hit a city.
It would be shot down. Near the end of the war, the Allies had aircraft capable of shooting them down. Of course, some could get through.
And most importantly:
V rockets=/=ICBM
Einstein left Germany because he knew stuff was going down.
I do not believe Germany detonated a A-bomb. They lacked the Uranium, manpower, and funding. They probably were able to do some small scale reactions and stuff. Show me your sources.
The USSR captured Lower Selsia, in Poland, and this area contained a lot of their nuclear program. The Soviets lacked the brains to do anything with it (Rosenbergs helped them). Operation Paperclip snatched a lot of the brainiacs for the US.