Every interviewer asks me if I have any questions at the end. I usually don't have any since we talk a lot during the interview.
Every interview is an exchange of information.
You are interviewing them as much as they are interviewing you. Always do research on the company before you go to the interview. This will help create the questions you need to ask in the interview. Do not be afraid to ask questions from the very start of an interview. There are several good reasons for doing this.