I went to the PHL event a couple of weeks ago. it was well organized and professional.
Expect to spend a good part of the day there; you'll get time to meet several folks from HR and the CP Office informally before the presentation and then a 15 minute face to face.
They'll send you a paperwork packet in advance; PRIA, Work History etc. Note the Drivers License check has to be Notarized.
Based on your 15 minutes in front of HR or a Pilot Recruiter you may receive an offer to interview onsite, or one later in Denver. They only have a handful of spots for the onsite interview.
It's a good opportunity to get a taste of the organization and growth plans, meet some people and sell yourself.
Good luck. PM if you want more..
//PL