Hi Bob,
First of all, thanks for the kind words. No permit needed to fish, but Queensland restrictions apply: No more than six lines out at any one time - Duh!! If you're worried about returning carp while being watched, my advice is to unhook in the water - that way you're not technically 'returning' the fish.
However, I have never killed my catch and have returned carp in full view of, and while talking to, Parks And Gardens officials. Most of the waters in the area contain a large head of carp to low doubles, with the odd lunker just waiting for your boilie! So give a go - you'll find Aussie carp fight just as hard as their UK cousins.
Tight lines, Dennis