Hi,

1. your retainers stay only a certain time on market iirc it is 4 days.... I think you items still would be shown but noone can buy it (had this experience when trying to buy a materia D: )

2. Your rested XP should be a full bar once you return. It maxes at a full bar so you still wont have endless rested xp.

3. I dont know I didnt take a break yet XD