Hello,
My family moved over here when i was 9, and i didnt have any problems, everyone wants to be your mate, because you are differant. I did have to repeat myself alot, apparently pom's talk to fast? The kids will be fine, the stories you hear about prejudice from Maori's are not that bad, and i havent heard of any involving kids. You are going to get the occasional idiot where ever you live, but new zealand is a great place.
Good luck with everything.
Katie