Hey, this is a great serious of questions.
On the miner question - you should start a thread in the Mining Support board on this forum, the good people there don't often cruise the Beginners board and most of the beginners can't give you the expert opinion you need to make your mining machining buying decisions.
On the Amazon spend question - You need to go through the company IPayYou as a conduit to use Bitcoin with Amazon Direct. Here's an article with the details:
https://www.geekwire.com/2016/now-can-use-bitcoin-buy-stuff-amazon-thanks-seattle-startup/