The only requirement is that you fill out and submit the base access form (MBAF) by the deadline, which is noon on May 14. This allows you to get on the base. If you fill it out and then can't make it to the event for whatever reason, there's no harm done. In other words, if you even think that you may want to come out, go ahead and submit the MBAF.
Once that's done, you probably want to fill out a registration form and print it off. Bring it with you to the event. There's no pre-registration, but it'll make it a little easier on you the day of the event. You might find it useful to read this (http://www.tirerack.com/features/so...dbook.htm)
so you'll have an idea what to expect, but there will be plenty of people there who can answer whatever questions you have.