As to where to live, find the area that fits your lifestyle. If you live the typical kiwi outdoor life, go where you can continue enjoying that. A lot of your social life will come through your husband's work contacts, so you'll need to be close enough to participate easily in that.
To bring with you:
-Jeans, sports shoes, underwear, socks, sheets, towels. All Argentine versions of these products are adequate (and by adequate I mean look good, last 3-4 months then start falling apart).
- Electronics. Ipads, iPods, tablets, laptops, some kind of e-reader as English book selection is very limited and eccentric to say the least (from Shakespeare to Jackie Collins with not much in between)
- kid's toys and books, it is hard to find good quality here and they are quite expensive.
- marmite / vegemite and maple or golden syrup. Even if you don't eat them they'd be good for trading with other expats.
- if you like cooking, bring any spices or Asian sauces you use. If you like hot cross buns you'll have to bake your own, so bring all spice.
Just about everything else can be found here. Things I miss are things I could never find here like feijoas.
If housing, schools and medical insurance is covered by the employer you'll have no problem with that budget.