Welcome to the Forum. Wilsons Prom and the Terrible Hollow are quite different. The Prom is mainly easy, all good tracks, highly regulated. The Terrible Hollow is mainly hard, mainly no tracks, no regulation. So perhaps you should define what sort of trip you want.
Depending on where you go it may be necessary to book well ahead (like The Prom) and pay to camp, or just go, no bookings, no fees. The latter is most of Victoria. Some places have camping platforms, like the Bogong High Plains. These need to be booked but most experienced people camp 100 metres away and pay no fees. Some platforms are badly sited, quite exposed.
With some limitations it's permitted to camp anywhere. This is part of the experience - camping in a new spot where no-one has been for a while. Fireplaces diminish this experience.
In general, fires are banned or frowned upon close to huts and in all alpine regions. Fires may be possible lower if there's enough wood, so popular spots do not have fires. There's a trend towards using stoves on all walks. Be very, very careful about fires on hot windy days. Starting a bushfire is ill-advised.
Look at Parks Victoria
http://parkweb.vic.gov.au/for more information.