Hi djc0. Another mover to Melbourne - brilliant! I hope you'll come to love my home town.

To quickly answer your questions - join Qantas (join from overseas so it's free), and Virgin Blue (free). Use Qantas/Virgin in Australia as needed, and UA for the US (or Air NZ if you prefer). If you end up with an Australian credit card that also gives frequent flyer points, it's 90% likely to be for Qantas.

Your specific questions have probably been answered but here's my take:

1. They're fine to give your loyalty to but they're a NZ airline, not an Australian one.

2. a. No. b. No. c. Yes, if you like going via Auckland (not quite as direct)

3. For travel to NZ from Australia, definitely (especially when they have specials). For the US, it doesn't vary much from Qantas and United because there is a monopoly in place for Australia to US.

4. Not sure, I'd say not. Others can answer this better.

5. As per #4

And to add #6 for you:

6. How is Melbourne to live?

Brilliant! Once you get over its sometimes temperamental weather you'll come to love its special events (Australian Open, F1 Grand Prix, numerous international and local festivals), it's fine food and coffee, and it's hidden treasures. Feel free to PM me with any Melbourne questions.