ExSp33db1rd, some of advice given to your wife is true, I have an iphone with a USA number purchased at an AT&T store by my company as USA is our most frequent destination.
It was locked to the AT&T network. But you can unlock them fairly easily from websites like this.
I tried this site and it does work, my USA iPhone is now unlocked and will accept any sim card.
However, you should be able to buy an "Unlocked" iPad from any Apple store. (You can in Australian Apple Stores) but you have to buy it outright. Not in monthly payments as a contract with a carrier will allow.
The new iPads, Version 3, 4 or iPad Air and the Mini iPads will work fine in New Zealand. Note the Global Gig website said their 3G device has issues in New Zealand but if you have their sim in an iPad it works fine.
It is true that the non sim capable iPads don't have built in GPS, only the sim capable models have the GPS chip installed. I can verify this is true.
I have an iPad 2 with sim from my company and it has GPS. My company later bought us non sim capable mini iPads and it does not have built in GPS.
I prefer having GPS so I bought my own sim capable version mini and gave the non sim version to my wife.
The Global Gig sim will work fine in New Zealand, USA, the UK with the included 5GB and no roaming charges, but the rates in France will be 20 cents per Mb.
Hope that helps.