Good luck with the license (you'll need it, from what I've heard).
Anyway, in Rotorua, you might get a look in with Volcanic Air Safaris who operate scenic floatplane flights (Twotter and Cessna 402 I think plus some whirlybirds). Then there's NZONE who are the skydiving operation, but I don't think they're interested in hiring and it's not floats anyway. Lots of helicopter operations in Rotorua too.