Re: Bombing Japan
Russia declared war to Japan *only after* the first bomb detonated on Hiroshima, on August 8th, 1945. They didn't declared war in May, after the defeat of Germany. They were in no hurry to help US and British troops in the Far East, the more they would have had to fight, the more they would have been weakened, and probably, an invasion of mainland Japan would have required to move troops and weapons from Europe to the Pacific - just like the invasion of Europe required to move them the other way, weaking the defences in Europe. Then, trying to take advantage of the situation, i.e. taking control of more areas of Germany, could have been feasible, or start communist revolts in countries like Italy.
Although Stalin was probably aware of the bomb, probably he wasn't sure it was already ready for prime time, and when Hiroshima was hit, Russians had to scramble to obtain something before the war was over.
That's why Japaneses consider Russian jackals even today.