Barely started, and pretty much shut down for lack of resources before the end of the war in Europe.
They were no way near close. We did not really know that until the war ended when we then captured their scientists and research data.
The Germans never got past the research stage, unable to attain a chain reaction.
They actually gave up experimention in early 1944 when their Berlin research lab was bombed.
They were a good way from it. The best they could have done by the end of the war was a dirty bomb.
This is seriously doubtful. Delivery systems in WW2 were lightyears behind the accuracy we have today. If anything, a trans-Atlantic missile in the late 1940s would have been lucky to have landed within 10-20 miles of its actual target. Toss in the weight of 1st generation atomic weapons (10,000+ pounds) and the small area of effect for a Hiroshima type device and the amount of damage would be extremely minimal. Remember, America had a nuclear project going on since the late 1930s and by 1945, America had only developed 5 or less atomic bombs.