Hi Mel,
I think where NZ is concerned it is purely a case of more people migrate from the UK to NZ than pretty much any other country. Some websites are dedicated UK to NZ sites, others (like this one) try to keep all information as universal as possible.

There is no problem with Americans being accepted in NZ, although there are a few rumours around! Most of these are just silly things like rich Americans buying up the coastline and building hi-rise buildings etc so I wouldnt worry! Its not serious and there are no hate campaigns!!