Hey mate,
1) would recommend just transferring rego, as it's a little easier. If you register as a new car, transport people sometimes come on look over the car, etc.
To transfer rego, you just basically have to get a RWC, go to a department of transport and transfer rego.
Registering as a new car, you have to get rwc as well, go to dept of transport, but they may want to check over your car. only difference
2) no idea about gold coast pannel beaters, sorry
3) chuck your n/a skyline up for sale. should get a few looks due to the new laws, and they seem to be keeping their prices really well.