Just a comment on travelling to WA....As someone from VIC that has done the WA tripquite a few times now - and this coming year too ! - it is always an awesome trip... you wont regret it.
Importantly, the longer you can stay, the better off you will be. Obviously that can be said for any windsurfing trip, but you can live cheap while in WA - thus allowing you to stay longer. If you can drive across, it is worth it - you can bring your camping gear and stay at Coro's beach for a month (@ $8 per person per night) or stay at the other local places.
Coro's does *occasionally* trough out... in which case, if you do have your own vehicle, then you can either drive north to some of the best Coral reef you will ever see, or head south. You dont need a 4WD to get to almost any of the sailing spots.
As for wind/gear - the local sailors dont usually have gear bigger than 5.5m ... that should give you an idea of the size gear to bring (either flying or driving). I was blown out on a 3.7m a few times this summer, with 4.2m being used about 80% of the time (@ 70kg).

.... and as mentioned, you can go to Shark Bay for some plain old flat-water blasting.