What, if anything, is going on at the start of the scene?

(1) Frankie and Cicci get out of the car. There's extra guys guarding the front of the house. Frankie asks "What's up?" and they gesture toward Bussetta, right at the front door. Frankie sighs and says, "We got company, huh?" and he advances on Bussetta;

(2) Frankie reaches Bussetta, who keeps his hands in his pockets, lowers his head, and does a quarter turn away from Frankie;

(3) Frankie walks past Bussetta into the house. His wife meets him at the door. Frankie asks in Italian something like "Who's here?", and she finally tells him Michael Corleone. Their daughter comes down the stairs at that moment, and follows as they chatter toward the study.

The wife and daughter I understand: a surprise visit from Michael Corleone is a rare and impressive thing. The rest of it, though, is it all just false mystery-building? Frankie's men are forbidden to speak Michael's name? Does Frankie know Bussetta, or why does he walk into the house without knowing who's in there?