We have just returned from sailing around New Zealand and have put together a 17 page pdf file with what you need to know to do this trip.

http://www.tenayatravels.com/files/Sailing%20to%20Fiordland%20and%20Stewart%20Island,%20what%20you%20need%20for%20a%20successful%20circumnavigation%20of%20New%20Zealand.pdf