Banks normally charge 2.5-3% as foreign currency converting fees. The rate is reasonable & you can not save this by using any other method. I am not quite sure which bank charges less. You can find this information from the websites of banks.
Any credit card such as Visa, MasterCard can be used overseas. It is very convenient and economical.
Travel card is a kind of debit card (cash card) in foreign currency. You have to buy foreign currency & deposit in your card. It is very convenient also. Ask your bank for details, most of local banks provide travel card.
ANZ Gold MasterCard (annual fee $80) covers international travel insurance.
The Warehouse Travel Insurance: http://www.twti.co.nz/?gclid=CM-5t5GW8KgCFQXabgod0n5OBw