When a guide dog is out of the harness they are just pet dogs. So at home a guide dog will act just like any well trained pet and will sleep, play, etc.
Yes, of course. Guide dogs are beautifully mannered and well suited to living in homes. If they weren't, who would want them in grocery stores and restaurants? While they need fresh air and exercise...
Then you get a new guide dog or retrain the old one. Preferrably retrain the old one because it might face what us human's consider the "death penalty".