If you go to Tassie put your car on the boat, it is alot cheaper than hiring and will extend your holiday if you need to come to Vic to put it on the boat.
Forest Glen in Qld is a good place to have a base. We stayed at the caravan park. It is close to alot of things, Australia Zoo, bee place, nut factory and not far from Maroochydoore.
Vic has alot of places just depends on the time of year. Northern Vic is usually warmer in winter
As for the snow all I know is that it can get pretty expensive, the chairlift is quite pricey.