It may have changed, but in my experience a so-called "international driving license" is nothing more than a standardized translation of your driving license, usually issued by the national auto club. It isn't valid except with your home country license - so since you're moving from one English speaking country to another, it seems kind of pointless.

Generally, they'll let you drive on your home country license for some period of time - say, six months or a year. After that, you have to get a local license, but there might be some form of reciprocity available. (Someone here on the forum should be able to tell you that.) I don't know Australia, but in some countries there is a special test for foreigners who are already licensed in their home country - in other countries, you take the whole driving test thing again.