I have never come across any information suggesting any rift between NY and those Families. But then again, I´m just an amateur researching the Mafia for the fun of it. Perhaps ScottD can answer that question?

However, the LA, NO and the Tampa Families does not appear to have ever sat on the Commission. I believe the La Stella Restaurant meeting in Queens, NY, which was broken up by the police and resulted in numerous arrests (Marcello one of them) was not a Commission meeting per se, but a formal request from Carlos Marcello to induct new members into his group. The meeting actually most certainly was held elswhere, but the restaurant served as a refreshment post either on the way to the meeting, or after the meeting had been conducted.

As of DeCavalcante, I strongly doubt that he sat on the Commission. As you say, he seems to have had only second hand info when talking on those tapes. However, he was assaigned by the Commission to deliver messages between the Commission and the Bonanno faction during the Bananas War. Him being a non Commission member, strengthened his reputation of being a neutral party in that conflict.