Hi Pip!
Ticket first.

Easier said than done, right? If you didn't register during the holiday pre-sale (which gets billed on or near Dec 19), get ready to register for tickets during the two-week period from January 9 (at 12 noon PST) until January 22 (at 11:59pm PST), 2012 on
http://tickets.burningman.com. On or before February 1st, you'll find out if you have been selected from that group. After that, it's an open sale of remaining tickets
More info in the link, and all over this site. (The more you read before you ask, the nicer people tend to be about helping you. "Radical Self-Reliance" is one of the ten principles of the Burn.)
Annnyway, never book anything you can't have refunded in full until you have purchased your event ticket(s). Last year, a few people missed the warnings about the imminent sellout and then were stuck with RV reservations and plane tickets but no actual event tickets.

Rough!
You can start making a pack list by downloading and printing the 2011 survival guide here:
http://www.burningman.com/preparation/e ... index.html
They give you a starter list, which for you will probably be a shopping-in-the-states list. You can also google Burning Man pack lists. Stuff you will probably want to bring from Oz: coat, clothes, goggles, 2 pair comfortable shoes/boots, prescriptions, anything that you can fit and want to keep/take home again or are very picky about--that sort of thing.