There was a sort of ceremony for Michael at the end of The Godfather when everyone came in and kissed his hand. I saw it as some kind of affirmation that he really was the legitimate Don. Same for Vincent.
Not really. There is difference between being made and becoming a don. At the end of the movie, Clemenza et al simply acknowleged their acceptance of him as don.
"Generosity. That was my first mistake." "Experience must be our only guide; reason may mislead us." "Instagram is Twitter for people who can't read."