For the past couple years, I housesat for my friends when they went on vacation. They always left me their cell phone #s, numbers where they could be reached at, their landlord's number, the name and number of their vet and any other numbers they thought would be important. It's nice to leave a note with instructions of how you want things done and what your expectations are. My friends had 5 cats so I would feed them canned food everyday, make sure they had water, clean the litter, etc. When they would come home from vacation, I would make sure the house was clean the way they left it. They always appreciated coming home to a spotless house. Hope this helps.
Sue