The heavy water experiments would have succeeded as Britain will not have knocked them out; will we have perfected our uranium bombs before Germany could have brought their nukes to use against us?
We had an ocean between them and us. No one had a delivery system at that time which could have reached across the ocean.
They would have probably used what they could against the Russians, but ultimately it would have done little good. The Nazis were losing behind the lines against the partisans and all the other thousand little irregular warfare activities.
And nuking the battlefield, which is what the Nazis would have done, would have hurt them just as much as the Soviets. No one had any idea what that weapon would really do. We at least had distance between our troops and the Japanese, there was little or none between the Nazis and Soviets, and Hitler would not have cared anyway.
The act of bombing the Soviets would have galvanized the USA into hyperactive research and activity, which would have given us what we needed to defend ourselves.
Most probably yes. While the Germans are excellent at organization. Their atomic bomb project was a disjointed and disorganized affair. Nine different agencies all had a hand in the program. The bureaucratic infighting between these agencies slowed production to a snails pace. Some of the scientists, like Heisenberg, may have been trying to sabotage the project. There effort at A bomb creation paled in comparison to our Manhattan Project.