When Michael was in Sicily, wouldn’t it have been easy for his enemies to find him? He even announced that he was hiding but he was unharmed for a great deal of time.

I tried to tackle this subject a long time ago by using the novel as a timeline guide. My conclusion was that Michael was in Sicily for far less than two years, and that probably less than three months elapsed between his being hit by the thunderbolt, and Apollonia's death by car bomb.

http://www.gangsterbb.net/threads/ubbthreads.php?ubb=showflat&Number=580389&Searchpage=1&Main=20650&Words=%2BMichael+%2Bin+%2BSicily&Search=true#Post580389

Only Sr. Vitelli knew that he was hiding out, but the entire village knew that an American with family ties to Corleone was among them because all of them were there for the wedding. From then, it was just a matter of (brief) time before word got back to Barzini, and Fabrizio was recruited to kill him.

What was Barzini’s end game? Take over the whole commission like Michael did and kill carlo?

If not take over the whole Commission, certainly dominate it. The novel makes clear that Barzini, younger than the other Dons, saw himself as Number 2, waiting in the wings for Vito to fold or die. He had already had Sonny whacked, and having Michael killed would leave Vito without heirs. He probably figured Vito would simply lose heart and fold, putting himself in the top position, Carlo would be a marked man--once a traitor, always a traitor.

How did Puzo come up with all the heads of the 5 families names? I’ve never heard of most of them.

What did you think of Godfather 3? Would Robert Duvall have been able to save it?