The event is Saturday, April 8. It's on the TR Autox Event Schedule.

Keep your eye on the NASA-X Florida website for the announcement when registration opens and you can pre-register. Yes, it's $40 for non-members. Yes, there are usually still slots available to register the day of the event, but if you can pre-register you should.

We try for a minimum of 6 runs at NASA events. Often we will do 7 or 8.

First-time autocrosser info is not hard to find. Check the sticky posts here on the forum for some. There's some on the NASA-X Florida website:
Car Prep
Driver Prep
Those are the basic novice tips. If you look on the website under "About Our Events", you'll find advanced tips, as well.

A very minor oil leak is not a big deal. Might be a good idea to clean up as much as possible before you come out (or maybe even try to fix the leak?) to minimize the potential for drippage.