Retreats are residential, with simple but comfortable sleeping accomodation. Most rooms are shared but you can request a single room if you have a particular need.
Retreatants help with the cooking and washing up (a good opportunity to get to know one another!)
The timetable is usually pretty relaxed, with a mixture of sessions of meditation, discussion, talks, ritual, and free time. The exact timetable and activities will depend on the retreat. But you don't need worry about having to sit for hours on end!