Can I foster only at certain times of the year, and can I say no if you call and its a bad time?
Yes and yes. If summers are great for you because you dont work, but the rest of the year is too hectic, then you can be a summer foster home. If summers are awful because you take long vacations, but the rest of the year is better, then you can be a fall-winter-spring foster home. You can always say that you dont want to take in a foster dog, for any reason.