I wasn't aware of the program, but it sounds interesting. New Zealand is a beautiful country.
I'm not a Kiwi, but perhaps I can answer some of your questions:
With regards to where the best places to live are, it depends on your lifestyle. Do you prefer living in the city or rural living? Would you prefer mild weather or are you ok with colder weather?
If you want warmer weather, obviously BC would be the best choice.
If you like living in the city, then your best choices are Toronto, Montreal and Vancouver. Ottawa, Calgary, Edmonton are also a fair size.
Toronto, with a metro population of about 5 million, is the largest city in the country with everything you could think of in a city. It has the third largest live theater district in the world, a major zoo, art gallery, museum, plenty of locations for sporting events, concerts, movies, etc. There's also -- and the --. Along with big shopping malls, it has an underground -- that's full of stores and food courts. When combined with the subway system, you can go just about anywhere in the downtown area while barely setting foot outside. Like other cities, however, it does get crowded during rush hour. Also, Toronto has been getting some bad press due to some gun violence recently, but it's far lower than a other cities of comparable size. In fact, its doesn't even have the highest crime rate in Canada despite having the largest population.
From what I understand, Montreal is less expensive to live in, but aside from that, cost of living really depends on how close you are to a city. If you live in a city, you're paying more for location, but you also save money that'd be spent on commuting if you worked in the city but lived outside of it. An apartment in Toronto ranges from about $700 to $1500 depending on what you're looking for. A nice 1 bedroom condo in a new building will run about $1100, but that also includes 24hr security, and lots of other extras that vary from building to building.
Here's an example of what the view is like at some of the new condos:
The building in this picture is part of --, which is a $1.5 billion project that includes 20 buildings and 100mbps internet connections. I'm not sure if they're renting, but people often buy condos as an investment and rent them out.
For what it'd cost to be in the middle of everything like that, you could rent a house just outside of the city, or save some money on an apartment. You can find less expensive places within the city, but be careful because, like other cities, Toronto does have some slummy buildings.
To get idea of what it's like in some of these areas, you may want to check out these links, which have lots of pics. They're from sites about skyscrapers so they focus on architecture, but you can see areas that aren't normally in typical tourism pics.
<SNIP: Advertising>
Most people coming to Canada choose the major cities, which is likely because that's where most of the work is, and the majority go to Ontario.