We went on the Pac Dawn too - we refer to it as 'our ship' now lol It's huge and alot of fun - most of the staff were brilliant too!

As for shore tours, once you're all paid up they send you all the magical blue folder with all the info in it and you can pick and choose the tours you want to do. Or you can wait until you get on board and book them then - but only if you want to (and if the popular ones aren't booked out) As you're hitting the Aussie coast you may just choose to use taxi's, buses or leg it and do your own sight seeing at each port. Or just chill out on the ship with half the crowd gone!