I would start with this thread. It'll cover everything you'll need. The only thing I'd add is front camber bolts as another "nice to have" item, but not necessary.
http://www.ft86club.com/forums/showthread.php?t=25485
In terms of helmets, every organization I've seen around here requires an SA2005/M2005 rated helmet (will likely switch to SA2010/M2010 after this year), but you'll want to check with your specific track and organizer.