Re: NFC
ISTR that the reason that Amazon don't tend to ask for the CVC is because the rules say that they must use the CVC instantly, and may not store in on their systems. Amazon only charge the card when they ship, and therefore cannot use the CVC on the order.
What I don't know is where other sellers stand on the consumer credit act, which AFAIK does not allow them to charge credit for something until you have it (but e.g. booking a holiday is not the same because you have actually paid for the booking, not the actual going).
I suppose that sites that store your credit card to re-use later (e.g. iTunes) must obviously use the numbers sans CVC for the later transactions.