To answer about GOR, there are no big trucks barelling at you. If u go when it's not holiday there, the roads are pretty quiet.
When I went in August there were stretches when we were the only car on the road.
Besides the constant pull outs, there is plenty to stop and do/see. Plenty hiking, watching surfers, water falls, sights. ... u can Def stop every 2 hours
I really enjoyed it and my kids as well. Was the highlight of our 3 week trip there. (I'm pretty sure I wrote a TR)
If u have time in Sydney I have heard great stuff about the caves there. U need a day for that. We liked the blue mountains.
There are other things to do based out of Melbourne, my family (parents, siblings andtheir spouses...) did some stuff like wild animal Park, bird Park, penguins, scenic spots. ...
The pictures they sent looked great but I don't know the names. I can ask if u want.
There is whale watching by the GOR but it's seasonal