Edge,
Im not really sure about your first question - Duncan? help?
Helmets - Any ADR approved helmet is fine! Sydney City motocycles have some good ones, I got my mrs a helmet there - saved $30.00 as I am an SAU NSW club member (another benefit to join!!)
And fire extinguishers - 1kg or bigger thats attacted inside the car close to yourself.
Just make sure the car is in tip top condition. No leaks, no loose items inside the cabin or boot. All fluids are good - oil, power steering, brakes - even bleed brakes if you can
You'll need long sleeve shirts and pants and closed shoes.
Im pretty sure thats it!