The important thing to remember during an interview is that it goes both ways, the person interviewing you is testing to see if you are right for the job, at the same time you are testing whether or not the job is right for you.
It is good to have a job, at 16 this can be a fine place to work, but don't just say yes to any job you can get, if you're going to spend a lot of time somewhere it's sensible to make sure the place isn't stuff and filled with starfishs.
Should I have a resume ready to bring in... Kinda forgot about that.
It certainly wouldn't help to be prepared, but if you're already going for an interview then they have probably passed that point by now.
Fast food restaurants get bulk resumes that are largely bleak and unimpressive, they don't care so much, it's not like you need a lot of previous experience to make fast food.