[curstpriest]

You can buy it in the US and register it there and ship it to her in AUS and it should work fine.. Can use the US store with US prices (should be cheaper too)

Just make sure wireless coverage is in the area.. They have a chart
If 3g isn't available, I think it falls back to EDGE or something, check up on that to make sure there will be coverage, otherwise just get the wifi version.

Regardless, using non-US bookstore will cost more I think..

You can use gift cards or credit card to access US store if that is an issue as well, and refill the gift cards periodically, I know a few people who do this.