I would definitely ask what the pilot rotation is. It is not normal for large departments to just leave the crews on call all the time, so there should be some sort of schedule.

Office time can be another big indicator. Good departments may have you come in occasionally, but never M-F.

How old are the airplanes and do they have any firm orders for new ones? How many pilots per plane? Is everyone PIC typed and considered a Captain, or do they have First Officers?

Those questions are a good start. They'll give you an idea of QOL as well as health of the department.