Call AA up, tell them you want to go to Australia from LAX and find out how many miles it will be for a flight 8-9 months out. Qantas is a OneWorld partner airline, so you can use your AA miles to book a flight on Qantas to get there.

Also use Qantas to fly from city to city in Australia, unless you plan to drive around but thats quite a drive. Sydney to Melbourne is drivable, but if you want to get to some other places like Perth or Brisbane (or New Zealand which you should also consider if you can take enough time!), may want to fly around to save time.

75k should be enough to get you there and back, might want to try and put spend on your AA card to get more miles for the city to city flights.

Australia is one of the places I most want to visit; hopefully get there myself in 2012