Hi Ezyjet2006,
It's good to see that you are doing a little research on Qantas and what to expect. It's a good idea to go into any interview with some decent knowledge of the company you want to work for. In this case, know a little about the Qantas network, know about the destinations you would be expected to fly to (mainly HKG, BKK, SIN), what type of aircraft we fly, etc. Don't go overboard, or you might appear to be a bit of a ****, but you shouldn't go in totally ignorant either.
Good luck :-)