The usual route is usually Cairns - Melbourne passing through Sydney, or vice versa. 1 month should be enough to cross the entire east coast, although with 60 days you can see more things and enjoy more. If you want to visit Alice Springs and enjoy the Outback, you will need a few more days to get there (or a mini tour with domestic flights). And if you want to make the complete return, through Western Australia and the Northern Territory, then you will need to spend more than 3 or 4 months. The west coast has some of the best beaches in the world, exceptional weather and incredible views, while in the southeast the cliffs offer great views, and among them are hidden beaches with perfect waves for those who like surfing.
Wine
There are several areas not to be missed: Margaret River in Western Australia, Barossa Valley in South Australia and Hunter Valley in New South Wales. Apart from these three areas, there are also vineyards in Victoria and Canberra. In all of them you can make free wine tastings and buy wine at competitive prices. One recommendation is to buy a box for the next 12 days. Dining with wine is a luxury that we did not allow for a long time!
Some of the more tourist towns / villages for backpackers are party sites. Broome, Byron Bay, Airlie Beach, etc. It is not easy to get out of the environment, especially if the accommodation is in hostels. If you are looking for beer party for 6 or 7 $ these would be your place, but if your style is more relaxed and you like to enjoy nature, it is better to avoid these places, and visit them only for the activities that interest you.
Australia is very expensive, the alcohol is expensive, and the food too. If you travel with your vehicle and kitchen you can save on costs, although the supermarket also quite a bit. The fact that the difference between the euro and the Australian dollar is very small right now does not help. An acceptable budget could be around € 40 per person per day if you save on accommodation costs but do camping in private camping areas. This budget can increase to 50 or 60 € if you do many activities like rafting, tours, or diving.
Finally...
For all those who choose to travel with campervan or car crossing Australia for remote and sparsely populated places, take into account the communications (Telstra is the mobile company with the best coverage in the whole territory, vs. Vodafone, which has a minimum coverage ), If you go on unpaved roads (in the middle of the Outback) they recommend to carry high frequency radio, and always carry abundant water and food.
Notions of mechanics will not hurt you either. The conditions are extreme, from high humidity to extreme heat. It is important to check the water, coolant and oil levels almost every day, and know how to change a spark plug, clean the contacts, where the fuses are, change a wheel or change the oil. The mechanics in some areas are very far from each other, and a tow truck 200Km is VERY VERY expensive.