1) Yes and yes 2) 4♣ is highly invitational 3) well 3♥, 3♠ should be forcing and I suspect initially inquiring about oM stoppers however 4♣ now implies either a shortage or a qbid. Note that 4M is either a 5x6y or x56y hand. Playing these as GF hand seems to make sense altho some will argue we should use 3M for those hands.