interview questions?

I'm completely new to journalism, and recently joined the magazine class at my college. My topic for my main story is on metal music vocals, so I decided to reach out to a local band's vocalist and interview her. She agreed to meet at their next show, at a bar. I already know a little bit about them, from youtube videos; they are popular in their area. My question is- what kind of questions do I form? Based on my knowledge already? Or should I try to ask some really basic questions for my story? I feel like I shouldn't ask her how she started if there is already another source that explains it- don't journalists have to do their research first to avoid asking the same questions? I'm just confused and nervous.