I think the title explains it pretty much. Also, I would have free tips on my landing page about a particular product and how to use it.
yes you can, but please becareful. if users don't like your ads.. fb could easily ban your campaign and even your account.. no matter how much money you have
I've found that that kind of traffic (from Facebook, Twitter, etc) is very low quality and has an extremely low conversion. High volume of clicks does not equal tons of sales.
You can drive traffic to your site from anywhere and show them ads on your site; this includes Amazon links. What you shouldn't do however, it use PPC or any other means to drive traffic to Amazon from a third party site.