Whilst Frankie Pentangeli should have had more faith in his Don, Hang out to dry - Frankie Pentangeli was....

Pentangeli against his own wishes, went to meet up with the Rosato Brothers at Michael's behest
It is a given that the Capo's widow and family are taken care of Yet noone from the Corleones bothered with the Pentangeli family whether Pentangeli died / disappeared?
Perhaps they did but Pentangeli was unaware, living in Army barracks with the FBI guys!

I found Michael and Ola's hand shake telling
Power play? It seemed it was Ola leaning forward to shake Michael's hand [Michael made no move towards Ola] after Michael told Ola "You tell him that's greatly appreciated!"

What I find somewhat confusing! Among others,

1. Why did Clemenza promise the Rosato brothers the three territories What was the connection
2. Why did Michael need to placate Roth because they were both negotiating a big deal together, important business Michael did not want disturbed
3. Why did Roth try to kill Michael as at that stage 'great man' Roth and 'wise and considerate young man' Michael were 'partners'
4. Tom as Michael's consigliere did not keep his ear to the ground [unaware Pentangeli not dead, Israel knocking Roth back etc.] Then again Tom only handled specific areas of the family business
5. The Corleone people with the New York detectives would have passed on such vital information “Frankie was half dead, scared stiff and calling out loud that Michael'd turned on him” straight away but to whom? as Michael and Tom had no inkling at all, stunned that Pentangeli was alive until the senate hearing
6. How did the detectives already had Pentangeli on possession, bookmaking, murder and a lot more even with the Corleone protection