1. Butterfly lamb leg is a great idea and really yummy - our local butcher will butterfly it for you so you may have a local that will too. You can also get butterflied spatch**** or corn fed chickens which are great and easy to cook too.
2. Hmmmm can't go past moreton bay bugs on the barbie but not sure how easy to source or $$ they are where you are.
3. Baked whole fish wrapped in baking paper then foil and stuff its cavity with big chunks of lemon, lime and dill. Score the skin and rub w a little sea salt and olive oil. Is very impressive looking too and everyoe just serves themselves off the whoole fish. Works well with fillets too, just wrap them as individual parcels and pop some slices of lemon / lime / herbs and salt and pepper. Goes well with a simple citrus, mango and red onion salsa.
Good luck!