Amazon do not sell the Edge themselves; you'll be buying from another company who trade through Amazon (Amazon Marketplace). Amazon handle the payment details, and then pass only your shipping address and details of what you ordered over to that company, who post it out. Aim for a seller with good feedback, avoid anyone who "just lauched" as you have no idea how they'll perform.
If Amazon USA is the same as Amazon UK then if anything goes wrong you first contact that other company. If this fails to resolve the problem, then you bring up a claim with Amazon themselves, who will ride in like a knight in shining armour to bail you out and give the seller a good kick up the arse while they're at it. Amazon UK are really good at that and defend their reputation fiercely, so I assume USA work the same way.