Here's one of the newer things Kings has been selling:
an aluminum cruiser frame with a built in tank
Looked around a bit at Craigslist/ Sydny- looks a bit sparse, like just getting going- it's a bigger deal here in the states and agreat place to get bike stuff locally.
Beach cruisers are good because theyhave lots of clearance- a lot of people use mountain bikes. I think a freewheel hub is easier to mount a sprocket on, but gotta have some caliper brakes squared away-
Good luck mate, my mother was from Bundaberg Queensland.