I suggest you check on tripadvisor.com for assistance with internal flights and itinerary.
I question the split AUS/NZ/AUS/AUS routing. Why not do all AUS and all NZ in two sections instead of 3? Is that due to Jetstar flights? Have you considered Hobart? You have 3 wks--what's your time frame/season? You're taking the right steps to work it all out, even tho you're still space avail on the long hauls. Keep working--you'll get it!