G'day Tom,
New members are always welcome in the mozzie class! <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />
I can be corrected if I'm wrong but to sail in the nationals you'll need a Yachting Australia Silver Card, Public Liability Insurance on your boat and you'll need to join the association which can be done at the nationals.
There is no dedicated Junior Comp. All sailors sail in either the Mk1 or Mk2 races.
Hope you find a good boat and join the class. <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />
Got the silver card apart of my Royal Geelong YC membership, been sailing lasers for a few years now. As for insurance can be orgainised quickly, and the membership has been 1/2 orgainised if i can get a boat in time