Dilnots Down Under

Hi, I am in need of some advice on how to start living down here! We arrived in brisbane a week ago and I had organised an air bnb for our first month to give us a chance to find a rental etc. Now we're trying to set up things like medicare, bank accounts and tax file numbers but I don't know what to do about address requirements! Any advice would be very much appreciated, I'm getting very muddled about what to do first and I don't think it's just the jetlag!! ?