Civil Aviation Safety Authority - Converting foreign licences
The above link may answer some of your questions.
I'm not from the dark side (CASA), but would suggest it unlikely they would consider your existing licence for conversion if it is not current.
Maybe consider all the above first, especially the costs, then identify which city you would plan to head to. With the exception of Canberra, all Australian state capital cities have a range of schools to choose from. Google can probably assist you there.