Nuremberg was unavoidable after the full extent of nazi crimes became known. There are a couple of good books on it, for example this one which I read some years back:
http://www.amazon.com/Justice-at-Nur...2527157&sr=1-3#_
On the whole, the trials were very fair and even most Germans agreed with that assessment at the time.
The biggest problem was that the trials were rushed and there was so much evidence that not all of it was presented at the trial.
For example, if the full extent of Speer's complicity in the slave labour program had been exposed, he would have been sentenced to death, as he should have been.
The only other sentence I would quibble with would be the death sentence for Jodl and Keitel. In their positions as chief of staff, they were not really in a position to give orders. A 20 year sentence would have been more appropriate.
As for what happened after the war, the initial plan was to have a whole series of trials and intense de-Nazification. However, once the Cold War began and the Soviet Union became the enemy, it became more important to concentrate on the present rather than dwell on the past.