Australia is one of those countries best seen from a car. for the visitor to Australia looking to get beyond the tourist sites and see the real Australia, then a road trip is a must.
It has been possible to circumnavigate the continent on seal roads. There is little reason to have a four wheel drive for much of the country, though anyone looking to explore further should definitely have an off road vehicle.
It is easy to find hotels and motels as you travel around Australia but if you want to save money then a tent is a good investment. Most country towns in remote areas have locations setup for people to stop over night and camp. Often for free.
Australia is big. You need months to do the whole country by car so don't be overly ambitious in your plans.