The cost of a restaurant meal including drinks will vary, but your bill should be roughly $100 and up for a couple, and a little more if you're at a fine dining establishment.
Expect to pay NZ$15 - NZ$35 for a main meal at a local restaurant, and NZ$30+ for mains at fine dining restaurants. A good hearty pub meal will be around NZ$25 for a main course.
Drinks cost between NZ$6 and NZ$12 for a glass of wine (depending on what it is of course) and a beer will cost you NZ$5 and NZ$10.
A bottle of wine will cost anything from NZ$30 upwards in a restaurant or cafe.