*Works with Windows 10 PCs, tablets and phones, Windows 8.1, Windows Phone 8, Xbox One and Xbox 360 (Xbox Live required). Not redeemable on earlier versions. Music: Only for purchase of tracks, albums and music pass on Windows 10 and Windows 8.1 PCs and tablets, or music pass on Xbox One (Xbox Live required).
It will be a digital code if you buy it online.
Yes. A code will be emailed to you. Enter the code into your Xbox account.
Yes you can, you can buy anything on the website with a gift card.
If there are no problems on Microsoft service side, you get the code instantly at checkout. If there is a problem they will be emailed to you and you can redeem the code in the Microsoft/Xbox store.
It will, through Gamestop website or your email inbox.
If you purchase it from the USA, it will be locked to users in the USA, vice versa for anywhere else really.