You need to lockwire your oil filter too, Mouse. If you are using a K&N, they have a hole to run lockwire through. If you are using OEM or other oil filters, the recommended way is to get a largeish hose clamp (plumbing section in Bunnings) which you tighten up around the filter, then lockwire the hose clamp to something solid. Can't remember the exact size, sorry, but it's something like 70mm?? At a pinch, you can join two clamps together, but it can be a bitch to fit both screw sections in. Better to get the right size.

Definitely cross-enter 600s and Clubsport! You get two of everything - practice session, quali, race starts (more is better, for practice), track time etc. Cheapest track time you can buy at $95 to literally double your track time! As Ed said, if you run out of energy, just skip the 600 race. Apart from a few fast boys at the front, you'll be racing against many of the same people in both classes. There's usually more of a time difference across the whole field in CS than in regular 600s, due to some guys running really old bikes and some having the latest legal models with fast engines (cough).

Shark fin is very important! Don't worry about an additional radiator overflow bottle (although i have one) - the stock one is fine. The overflow is actually supposed to go into the airbox, but it never gets checked.