My first option would be bank wire - though old school, but its the safest method which I trust. The alternative solution is perfect money - easy and convenient, and most brokers seem to use this payment.

Deposits & Withdrawals, Skill (eWallet) or Bank Transfer?

I suppose brokers which are regulated in ASIC or FCA are good enough, not necessary have to look for brokers that are in New Zealand?

Any Good New Zealand Brokers

I think every broker has a portal for you to log in and check how many lots are completed within that account and for the duration you're interested in. For mine, when I click on my commission it shows how many lots of FX, Metals or CFDs I've done, ...

Volume rebates