Hi,
If the DUI was in the last 5yrs then YES you have to disclose it to the insurer, they then decide if they will cover her whilst she is driving, you will have to provide the reading and if she lost her license for how long.
www.nrma.com.au
www.aami.com.au
Are a couple of the big insurers over here, this should give you some idea of the prices, it also depends on Year of Car, Make of Car, where you live and your Age for the quote, these are the main factors. Foreign cars tend to be higher to insure, so do your homework on the insurance front before buying your car when you come over.
Also bring over proof of you NCB to pass on, the company I work for do not need to see this proof as we rely on your driving experience and history, but some companies may insist. Another thing to remember is to bring over your 'Roadside assistance membership' as they are reciprocal and you can join over here getting the joining fee waived and keeping the number of years you have accrued.