Whenever you do decide to go, take lots of sunscreen and wear it even if the sky looks grey! I got sunburned there on cloudy days!! Rotorua is good to visit, you can see a kiwi bird, see the geysers, have a hangi and watch traditional Maori dance. It does smell like rotten eggs there though so be prepared for that, the air is full of sulphur.

Between Christmas and New Years .... in my opinion. But it depends on what you want to do. If you want more snow/skiing, then July.

When are you planning to go? There is a government mandated 2 week quarantine atm that doesn’t look like they will lift for a very long time. It’s $3k. Also unless you are a returning citizen unlikely they will let you in. I’m from NZ and happy to recommend once I know what time of the year you are going and what your interests are. It is an out door paradise

I've been here for over a year now, and honestly every season has its perks.

Depends what you're into. Summer (November-March) will be lovely beaches along the north island, and amazing hiking down on the south island. In the winter there is ski season, and there are still awesome beaches.