NZ Questions.

Hey Everyone

I'm needin a helpin hand.
I'm really wanting to travel on the Grand Explorer in September 2007. I'll probably be goin alone, its gonna be a first for me.
Just a few questions..

Spring in NZ.. Is it quite cold, or warm? I live in Perth - so I'm use to the heat. Should I be mainly packin jumpers, and jeans?
Should I be using a backpack, or suitcase with wheels?

I wanna try skiing in Queenstown - Do you know approx ammount it'll be?

Do we need to pay for optionals upfront in cash? Or can we use EFTPOS and credit cards?

Thanks xo