Your presentation will last around an hour. There will be alumni from the program there, including your campus reps. Your recruiter will be there, along with whatever trip partners are there.
During the presentation, remember that they are watching you! Look interested, ask questions, talk to some of the reps and alumni about their experiences after the presentation. One thing that's true about CP alumni...almost all of us will talk your ear off about our CP with very little prompting. Bone up on your Disney trivia before you go...you might have a chance to win a small prize.
It's great that you've already filled out the application!! Watch for posters to start appearing around your campus pretty soon. Also, if you have a student union, watch for info tables and things like that. Meet your campus reps! They're there to answer any questions you have and are a great source of information! If you don't know who they are, tell me what school you go to and I can PM you an e-mail address.
Be prepared for a group interview; often they're done in groups of three or four. If you have a resume prepared, go ahead and turn that in with your application. If you don't have one, don't worry about it. It's a nice touch, but not absolutely necessary. Remember that it is a job interview with a Fortune 100 company! Dress appropriately and be there early. Make sure you know where you're interviewing beforehand.
You may have a chance to interview the night of the presentation, so bring your application and dress appropriately for the presentation, too. You'll be given a couple of forms, one that give the recruiter a little more information and one that describes the roles available and has you rate them according to your interest. Make sure you read the roles sheet carefully, and be honest! If you don't want to work quick-service food and beverage or custodial, be honest about it. It's much better to be honest about it in the first place than to be unhappy with your role once you're on the CP.
As for the anxiety of the wait after the presentation, I don't know what to tell you. I went on Spring Break (to WDW, no less) the week after my presentation, and had everything waiting for me in my mailbox when I got home! If you look around on the web, there are tons of WDWCP message boards (I run one; link's in my profile -- it'll be down for a few more days, but it's there!) where you can commiserate with others who are waiting.
The likelyhood of your acceptance is near impossible to determine. It depends on your recruiter, and where they think you'd go best, and whether or not there are opportunities in that area.
Good luck! If you have any more questions, there are also quite a few current campus reps on the board. I know Jimmybop is a rep, so am I.
Well, it was TRUE (here I am singing its praises 29 years after my first visit), and it apparently worked! 
Yep, I'm an alum of the Spring '90 WDWCP! Truly the best time of my life!
and everything Disney. Some people say I am obsessed. LOL 
In fact, mostof the people who got in from that group were from the other schools, not the school it was actually held at!
