I thought id like the events crew answer this one, but its been here for a few days so ill have a crack...
Pay asap, sooner the better to lock down spots...
You need long sleeve shirt, sealed in shoes & full length jeans/trousers...
In short wrist to toe clothing, so the only parts of you exposed are hands & head/face...
As for helmet regulations, you can use any type (motor cross, motorbike, open faced, rally, circuit, drag helmets are all acceptable)...
It must have an Australian standards sticker on it at the back... (The five tick sticker, like the one below)
Thats it... Just remember to have fun!!!