5th April... I got this on my visa before, visa and 90 days not on pair, and it was like two months off, I asked them why I have to make 90 days after 30 days off renew my visa. Answer 90 days report count separate.
They have your biometric data, fingerprints with ur Aussie passports, if u try to come with ur UK passport so ur Aussie passport show up... Don't know if it's good but i can believe not.
U need to make a passport for the car at transportation department, at the border u need to make a insurance, and as i remember u need 3 sets of copies, passport, passport from car and so on. The passport need like 2-3 days and is valid as long your toad tax.
then let us know the cost, how much the agency charge. I did it once, this agency charge for retirement 15k and for marriage 35k, because they can't do it here, they will take your passport to another state, not remember which it was, if you below 50, there is no retirement option.