There are 2 in-person interviews. The questions they will ask you are very standard and easy to prepare for - pretty much any question you can find if you google "common job interview questions" will be asked. Of course they will ask about your musical background as well. I would strongly recommend spending time in the store and getting to know the employees before finishing your interview process if you haven't already. I would argue that the bigger part of the interview is to gage your personality to see if you're going to fit in and work well with your potential coworkers. You can be qualified as can be, but if the interviewers has any reasonable doubt that you may not mesh well with the group, nothing else really matters.

You get a couple of interviews, one with the assistant manager, and one with the actual manager. Questions are fairly straightforward and pertain to the position you are applying for.