Hi there,
It depends on where you decide to settle in NZ as to the cost of living. Auckland tends to be the most expensive, although income also tends to be more to compensate. I think the cost of living here is high in comparison to earnings but we came here for the quality of life, which now have!
A 4 bedroom home can vary depending on the age of the property and the area, but expect to pay between $360 - $500 / week. Electric is approx $140 - $200/month depending on the time of year. Water is mainly included in the rates which the landlord pays if you are renting. Some areas ask you to pay for the metred water. We pay for a land line and broadband connection which is about $80 / month + calls. Fuel prices are also on the up. Our average weekly groceries for a family of 5 are about $300, but we can reduce this with some careful planning etc. I think you need to bring home about $1000 / week to live comfortably, you can manage on less and more would be good.
Good luck with your plans.