You can have the equivalent of a mobile phone in a laptop. Slightly quicker than 56k dial up. Expensive in terms of usage. Use a normal phone line wherever available.
For Broadband, I think it's Bluetooth, but I may be corrected here. You would have to be in a hot-spot for this.
Don't worry about being from Australia, laptops don't know what country they are in.
Boot up and shut down - same as a desktop.
Battery life, should see you through a working day. In-car chargers are available.
When travelling with a laptop, don't carry it with the laptop case on view. Put it in a rucksack or something. And don't leave it on view in a car.