The Iphone is nationally supported at AT&T and Verizon. Although it is not recognized by cell phone companys you can have your Iphone unlocked so it will work on any GSM network globally.
Get the iphone
Most cell phone spy software is installed on phones and NOT computers. So unless you are talking about the iPad you must be referring to the iPhone. Yes, you can use cell phone spy software on the iPhone, but you must jail break the iPhone first. Sites Used To Answer This Question http://spybubblefree.co/spybubble-free-download-for-the-iphone-really/
It could if you have the right adaptor.
Your cellphone might not work in Australia because they do not have many of the phone companies that we do in our more modernized countries.
You should consider purchasing the Apple iPhone. If your carrier does not carry this phone you can always have it flashed to work with your company that you use.
A headset for a cell phone is an optional accessory as it is not required for the cell phone to work. All major cell phone companies do sell some type of headset compatible with their product.
The iPhone is a pda aka a smart phone.
The best ones for reliability and cost are the Iphones. The droids have a lot of quirks and don't always work with specific things. Where as almost everything works flawlessly with the Iphone.
It depends on your needs. One of the best period is the Iphone 4s, but if you want a work phone (depending on if you have a pc) a windows phone may be best.
Yes it will
Apple will sell you an iPhone but you need to have a service plan for the phone to work. People auction off old iPhones on EBay and Amazon has used phones as well. Basically, you can get the phone anywhere but get your cellular service from sprint.