Melbourne to Brisbane ...... My experiences comes from Sydney to Melbourne.
What time of year are you leaving? Winter is much quieter tourist traffic wise, summer is an extreme gong show. It's a lot of riding the Princes Highway, usually good shoulders but it can be extremely busy at times. Not a heck of a lot of options for different routes either if your sticking to around the coast.
Money wise, I was spending about 30 bucks a day usually just free camping, eating rather well, cooking 2 meals a day. NSW has a lot of nice campgrounds along the coast, sometimes with hot showers to stay and good roadside stopping points. And in every small town along the coast there are free showers near the beach for the surfers to rinse off....
Gear wise, this one is totally up to you. There is really only once 200 km stretch that doesn't have a heck of a lot of facilities in southern NSW, but the rest of the route has a town no further than 50 km from the next. Bring rain gear, clothing warm enough for lows of about -5C (winter, inland) and minimal spare bike parts (lots of excellent bike shops around).
In Victoria there are lots of Rail Trails around, highly recommend them.
Also, it's bloody little hill country. You'd be shocked on how many times a day your going up and down. Nothing difficult or huge, just the quantity.