Paperwork Help! (Christchurch)

Hello,

Our family is moving to Southland in May. I'm wondering what we need to bring for paperwork for taxes and customs. Our visas are approved. Will we need to show anything other than those at customs? Such as proof of employment, medical exams, etc.?

We moving from America. Will we have any reason to bring American tax returns with us? Help! :)

Thanks!!