It sounds like you guys are being well taken care of, but I thought I'd throw in a couple of recommendations from our stay in Sydney. One is to visit the Aquarium. It's an EXCELLENT aquarium, and gave us a great orientation to the kinds of critters we'd be expecting to see when we dove.
Another is, no matter how touristy and dumb it seems, the Sydney bridge climb. It was incredible fun, and the view from the top of the bridge out over all of the city gives you a very cool sense of how Sydney is laid out, and how much WATER is in the city.
You will have a ball. We absolutely loved Australia, the country and the people, and I would love to go back.