I answered some of this in another question, but in terms of how the meetings are arranged - the meeting schedule is set, and then we try to find hosts and locations. It is sometimes hard to find hosts for 50+ people for 3 days! Then we build the agenda on GitHub (you can watch these agendas here), and follow the agenda during the face-to-face meeting.
At a high level, the face to face meetings are all about getting consensus. We never vote, we only proceed with unanimous consent. In practice this might mean someone doesn't like the direction but isn't willing to stand in front of it. But it also means that delegates have to work hard to bring along the entire committee, not just a majority necessary to win approval for a feature. This is TC39's most awesome aspect, in my opinion. It ensures that everyone work together in good faith toward mostly common goals.