1 - New Zealand
2 - New Zealand Dollars
3 - $100-$150 (about 80 - 100 USD)
As for 4, its about $3000, but that doesnt really tell you anything. What really matters is your disposable income. Say I earn $100 p/w, and you earn $700 p/w. However, you have a mortgage, a wife and a kid to feed, car payments, bills etc. In the end you might have $50 to spend on things you want. I, on the other hand, have no responsibilities, so I can use that $100 to buy whatever I want. That means I have more money in the end even though you make more. And since youre dealing with many different countries, youll have to know things like food prices, living conditions, house prices etc. Maybe they have expensive video games but very cheap food, so they can afford it. Knowing how much money they make wont really help if you dont know what that money can buy them.
Sorry if I sound like a prick, I just like thinking about this stuff