Stage 1) An assistant director or owner will go over your application and resume with you. Essentially, they are feeling out your personality--what drives you, do you play well with others, can you handle pressure, and, most importantly, can you learn.
Stage 2) If you are deemed a fit with the culture, you'll be sent out with one of the corporate trainers to be interviewed in the field. They will ask some similar questions to the first round. They'll also explain their pay structure, scheduling, and make sure you understand that you're walking into a sales job that plays the numbers.
Stage 3) If the corporate trainer feels that you're trainable, you'll be brought in for a final interview with the owner or one of the assistant directors. This seemed a formality to me, but it is actually one last check on your personality as well as a check on your ability to retain the information you were given in round 2. You'll be given an offer at the end if you don't make yourself out to be a total dunce.
The three things they are really looking for are work ethic, motivation, and student mentality. Of the three, student mentality is by far the most important--if you are a good student, they can teach you the other two.