two things: Painters tape (I'm sure it was posted and that I just missed it) and Teflon tape (useful for nuts or bolts that like to work themselves off, just put a little on the threads)

 

I think gloves and safety goggles are the most important. Other than that you can get a really good starter kit from sears. craftsman tools are amazing. I got a good started kit on sale for about $100. I would get a kit that has 1/4in, 3/8in, and 1/2 wrenches and sockets. Other than that most of the tools you will just pick up over time as you need them.

 

If you don't already have a jack, you can get an aluminum racing jack from Harbor Freight for 100 bucks. Don't forget jack stands.

 

Nice pair of Needle Nose Pliers.
2 sets of 6 point sockets and 2 ratchets.
1 set of smaller sized sockets with smaller ratchet.
A not cheap torque wrench, I broke a cheap one while trying to torque a wheel back on.
C-Clamp for brakes.
1 set of ratcheting wrenches.
Impact Hammer.
A set of screwdrivers in both styles.
Snap-on Hex key set (or whatever common size they are called if not hex).
Wire stripper/crimper.
Scissor.
Knife.
Sharpie.

 

23mm open ended wrench for diff fill bolt, magnetic tray, magnetic grabber (for when you drop screws in those tight places), LED shop light, shop towels, gojo.

 

Two bolts that can be used to extract a brake disc...don't know what size they are, but probably about 75cents at Home Cheapo.

OBDII scan tool (~$100)

LED flashlight on a tripod with 6" bend-able legs (~$35...kids got me one for Christmas,that thing is awesome!)

Dozen-or-so nitrile gloves (keep your hands clean at the track, or "play doctor" afterwards depending on how you roll... ;-)

 

I think its 24mm. But does a 1mm difference even matter on that bolt (honest question)?

 

This.
I picked up a $200 (maybe $300) tool set from Sears. You will never be able to piece together a tool set for the same price as the Craftsman sets they have. Add in a breaker bar and you are good to go.
As others have said, just piece together other tools as you need them.

I guarantee this will give you the best bang for your buck.

 

I originally read that it was a 24mm to drain and fill. Nevertheless, on mine (MY00) and 2 of my friends (MY01 and MY03), the 24mm would fit the drain bolt, but 23mm was it for the fill bolt.

 

I can't emphasize this enough! 12 point sockets will ruin tightly torqued bolts.