Hi Footy
To do all this you will need the 4 weeks the trip around the coast will take 3days from Sydney to Melbourne . When in Melbourne you will want to drive the Great Ocean Road as far as Warrnambool and the go back to Melbourne the inland highway 2days for that.
In Alice Springs it is best to take bus tours to see places if you look up
http://www.aatkings.com they will give you tours and prices there are others to but we have use them and found them ok .
From Brisbane to Cairns it is a 1700KLS drive so you will need will need about 7 to 10 days to drive and see things on the way
web sites on Australia
http://www.australianexplorer.com.au
http://www.traveldownunder.com.au
http://www.travelmate.com.au
For the cheapest airfare for the day and time in Australia is
http://www.farehunter.com.au
Just add tax on Jetstar prices and some of there flights do land at Averlon air port it is half way in between Geelong and Melboune
As I live in Australia and have been to all these places you are going to so if you want more help just ask.
What time of the year are you planing this trip as it is very hot in our summer in the centre and in the north of Australia.
______chubby_____