Ask how long they have been in the Quad Cities specifically. Storm chasers roll in after every hail event, do a hundred roofs on the cheap, and are gone before the first warranty claim.
Ask who is going to be on your roof. The name on the truck is not always the crew doing the work. We use the same crews every job because consistency is how quality happens.
Ask for the written workmanship warranty in advance. If it is not in writing, it does not exist.
Ask if the owner will walk the finished roof with you. If the answer is no, you already know how the rest of the job is going to feel.