Ricky as Johnnilicte said, just stick to NSW cause it won't be worth the hassle nor the money to get the car re-rego'ed here in NSW. Also bear in that if you get it re-rego'ed, from memory you'll have to go through the whole blue slip process again. That means more things will be nit-picked and you will have to fork out even more money to get the car back on the road with NSW plates.
When it comes to previous accidents, the way I see it is that the panels are like the clothes of the car. Clothes will always have a chance to be damaged, but so long as the rails and the inside 'guts' of the car is tidy and the repair job is good, then that's all that matters. Remember most of the cars that you'll be looking at will be 10+ years old. I highly doubt there are liners out there at that age that hasn't had even one minor prang, unless it's never been driven and was stuck in a garage somewhere in Japan.
Sometimes you may get lucky and find a good example for a good price straight away. Other times you may just have to be patient.