Post 1988 cars must be owned by you for at lease 1 year. You will first need an import approval from DOTARS (dept of transport).[ The car will need to be modified to australian standards (possibly seat belts and some lighting) and signed off by an automotive engineer.An austrlian compliance plate can be applied for and fitted) after that the car can be registered.
Would be happy to help out at this end with advice ect. Although I am in Melbourne.
Yes I think that your cars now have cats, intrusion bars and things like that.
Cars with back seat must have child seat anchors. Most likely seat belts and headlights will need changing. All should be easy thhough. Just get your import aproval first, before shipping the car.