How do I respond to an inquiry for my listing when only a name is given (no email address) ?? I did not see anyplace to answer his questions.

Don't feel dumb. It's not you. When he responded and left no contact information, the other dude is the dumb one. When he sees your car and is interested, he sees what contact information you provided, and it looks like you are going to have to wait to see if he sends you another response. Unless there is a "reply" box where he asked you questions.