My advice would be:
1. Buy tickets for the entire length of your stay - even if you don't think you will go to the parks every day - it's cheaper to buy here for a longer period than to buy a day here and there once at the gate. (And often it's fun after being out and about for the day just to go in and watch the fireworks).
2. Although flying Air NZ will save you some $ - the flight, I think, works out to be about 4 hours longer than Qantas. So consider the money vs time factor. Also Qantas gets in early in the morning (7:30am) so it give you a whole day.
3. Check out some of the great books that are available - you can get lots of great tips from them, as well as on the boards.
4 Don't think you have to stay on property to be close to the parks. If money is an issue, stay at one of the good neighbour hotels. (I always stay at the Fairfield Inn by Marriott.) There are also some great restaurants on South Harbour Blvd
5 With the Aussie Dollar so good at the moment, as you save some extra cash think of exchanging it into greenback - that way you will not be able to spend it at home.
I love Disneyland - it truly is the happiest place on earth!
I have some old park maps (from 2005) - PM me with your address if you would like me to send them to you.
Enjoy your trip, and good luck planning it - the planning is nearly as much fun as the trip!