First,
I wouldn't ask a lot of questions.
Second,
The questions I would ask, are the things the reason I went on a ride along for. If you have no questions, what were you hoping to gain?
If you are just blanking, however, I'd want to know about how he felt about various things. I'd be interested in hearing his rationale for the decisionmaking process he uses. And, I'd want to know what he felt about the community.
What I wouldn't ask are questions about equipment, rank, his career aspirations, how to get out of legal action, where the best dope to buy is, can we go by my school and let me drive, can we arrest this kid I don't like, has he shot many people, will he shoot someone today, can I have my own gun, you know, just in case? No, ok, well I brought my own, that kinda stuff (I have seen every one of those questions, btw)