I went to passholder preview as well. We learned a lot of stuff. If you want to try out for the show, you will be able to sign up online three months in advance. They are going to pick 18 people a day to compete in six different shows (and two back ups), and the finale show will be all the winners for the day.
Each show will be 20 minutes, and the finale will be a 40 minute show. There will be judges, but their opinion doesn't really matter. It's just the audience vote that determines who wins.
There will be 113 songs to choose from. There will not be any repeated songs during any shows of the day, so it's best to schedule an early audition time so you can get your pick of song.
And, I was there today, and someone was filming in the queue area. He might have been a past contestant on AI. He had very bushy, curly brown hair. (I don't watch the show.)