I've been to all those places,and a word from the wise is this: If you are going to Australia,go for 3 weeks minimum,and longer if you can. It is a very big trip from the USA,and Australia is also a very big country. I'd recommend going for Christmas,then follow World Series Sprintcars then do the big races late in January,The Kings Challenge, The Grand Annual Classic etc. in between the wingless races. I'm going on past memory,as I dont follow the racing scene in Australia as I once did.
In the meantime you can always get in touch with the folks at Global Speedway Tours.
http://www.globalspeedwaytours.com.au/ You might have seen them here in the USA at a couple races at Sprintweek,Kings Royal,Knoxville etc.