Yes, they would heavily focused more troops on the western front and force Great Britain into submission.
No, the United States would of eventually overwhelmed Nazi Occupied Europe. (Perhaps a nuke?)
Invadimg Russia is.like stepping on a landmine. You either die a swift violent death (like Nazi Germany ) or you loose a limb and die slowly (like Napoleon )
Also, If Hitler had continued funding his rocket, jet, and biological warfare studies, he probably would have taken over a lot of the war.
American industrial capacity plus internal resistance on their end, not to mention a large portion of the population ceasing to be, would end in their getting ripped apart. Area 11 would still get nuked, though.
I disagree with the description however. The Soviet Union was in the midst of massive mobilization when hitler invaded in 1941. By 1941 the Soviet Army would have been fully mobilized and stronger than even the Wehrmacht. There was no way the MR Pact would last given the polar nature of the Soviet and German governments and ambitions. If Hitler did not declare war on the Soviet Union, Stalin would declare war on Germany. The US's involvement is still largely irrelevant militarily, although since the war might have lasted longer in this scenario, the bomb could have been detonated in Europe. Operation Sealion, however, was destined to fail given the Germans lack of Naval Superiority in the Channel thus rendering it impossible to transport divisions and supplies.
Let's get away from all the economics and what-not and focus strictly on the one thing that plagued Hitler's war through its entirety; Hitler. He was such a narcissist that he did not bother listening to the experience of ANY of his commanders at ANY point. The German commander on D-Day actually correctly guessed the Allies invasion plans and locations, but Hitler did the exact opposite of what was suggested which paved the way for ally victory. This continued throughout the war so it would not have mattered in the slightest, he would have tanked it anyway.