Do items in houses respawn?
Important and unique items won't respawn. So skill books, keys and the like wont be found a second time.
You can find up to blue-level randomly in the same area when containers respawn. I know that only tribute will respawn in player housing, but I haven't really payed attention to respawning in other houses. It seems to be on a different timer than the rest of the area.
Futhermore house respawn may be delayed it you don't loot the whole house.