I'm with PG on this - call! Make sure your questions are sincere, though. As he says, questions designed just to get you noticed are more likely to annoy the hiring manager than they are to impress them.
If you decide you still want to apply after getting your questions answered, you can always mention your call in your cover letter. If you decide you don't want to apply, you can mention that during the call. ("I see. Unfortunately at this time I see my career going in a different direction. I appreciate your time, though.")
As far as telling the hiring manager about yourself, I'd have my "elevator speach" ready to go, but I'd wait for him to ask for it. Keep your focus on your questions until you're invited to do otherwise. ("My name is ____, and I'm considering applying for the position you have advertised in xxxxx. My I ask you some questions about that position?")