Basically in the South Island of NZ, you have two places where you would want to live and ski (no Methven does not count), these places are Wanaka and Queenstown. Wanaka has 3 ski areas nearby, Treble Cone, Cardrona and SnowPark. Queenstown has Remarkables and Coronet. Everyone lives in Wanaka/Qtown and drives/gets a bus/hitches to the mountains everyday, so the social scenes are focused in those towns.
Wanaka is quieter and smaller than Qtown, but has more of a ski vibe. The ski areas are probably better over there too, but you can't get a pass that covers them all, so it'd be pretty expensive to ski them all. Qtown is a party town, which is super fun to live in. Remarks has a decent park, and fun steeps too. Coronet gets busy, but actually has some fun stuff when there is pow, you can get both these mountains on a really good value pass.
I am a little biased because I have lived in Queenstown for 4 seasons and love it there.
As for jobs, I instruct and love it, but I don ski for myself as much as people who work in restaurants/bars etc. If you don't already instruct, I would say those are the jobs to go for. Unfortunately they are hard to get ahead of time, you have to turn up early, and be lucky to find a good one. Mountain jobs (lifty, f+b, rentals) have the benefit of giving you a pass/transport/sweet hookups, but the reality of many of them is lots of work, not much pay, and only 2 days to ski a week.