I would definitely stay for a longer period of time if you like New Zealand. It’s one of the more easy countries to adapt to, with good facilities.
A working holiday visa is not for everyone, it’s limited to people that are aged 30-35 years. When you have passed that age, you can’t get a working holiday visa anymore. The easiest visa to apply for next is a Tourist Visa. However, with this visa, you are not allowed to work, which is a bit hard if you want to make money too.
Take it easy the first week of your arrival. Then the week after, it’s time to arrange a bank account, tax number, and transportation (a car or van is most common).
You are free to go wherever you want. Oh, decide whether you want to work in the South or the North Island because crossing to either island takes a couple of hours by ferry.
So just apply for a visa, book a flight, pack your things and go!
Do check if your passport is valid and get an international driver’s license if you want. Finally, also take a credit card, just in case.