If you plan to do a lot of windsurfing you would be best to bring your own gear out as I was talking to a Belgian guy the other day and the prices in Europe are much cheaper...However, check the restrictions etc with the airline before you book. IF you want to do the cheap version you could hire cheap campers out here or if you have more to spare buy something cheap and resell before you leave.
Camping grounds cost around 25-30 Euros a night for camping...you could try staying in the van at given destinations but sometimes you could be asked to move on or even fined...On the eastcoast of Australia at least they dont like people staying overnight in vans whereas in Tassie they actually encourage it in many towns.
IF you wanted to touch base with some fellow European tourists you could try putting an ad in www.gumtree.com.au as there seems to be heaps of "backpackers" etc looking for travelling companions etc.
Sorry, cant help with gear questions as I am a newb myself.
Here is a site to get you started on some of the colloquial language but some of it can be very regional depending where you are (NSW/VIC/QLD/WA etc have different terms for many things such as beer sizes and even names of fish etc).
www.koalanet.com.au/australian-slang.html