I was 18 when I interviewed, never had a job before, showed up in shorts (I didn't know any better until I went to college). I originally went in to pick up an application, the manager was there and helped me fill it out and set up and interview time then and there. She was nice and was glad I was flexible with my time (they weed out the serious applicants by asking availability and most times if you are not available for at first and second shifts you won't get a call back. I interviewed with the assistant manager, he gave an over view of what was expected which was basically making hoagies, serving customers, and stocking shelves. He didn't ask about my previous experience because I didn't have any, I also didn't have to provide references. Then i interviewed with the manager and she basically said the same thing as the assistant manager. There wasn't any questions involved it was kind of implied i had the job. A week later I filled out the paperwork and started working.
Now there is a phone interview and you have to fill out the app online. If you don't give a good impression on the phone then you won't be called in for a real interview. Also, managers like steady people because their hiring/firing is monitored by the district manager and if the ratio is too high then it looks bad on them.