Do you have any questions for us?

I never would have thought of "Find out where they recruit talent". At first I thought that might be a good question. But your interviewers could namedrop contracting agencies or say they go to the UG meetings and other meetups, and the place could still suck. Useless question imo.

Something of critical importance is to do your best to judge morale. In fact, a simple question of "How is your morale?" is easy enough. If those that you ask that can't answer that immediately, or you they just can't convince you they are telling the truth, something is definitely wrong.