Amazon FPS (flexible payments system) in a nutshell

A few weeks ago I looked into Amazon FPS (Flexible Payments Service), just to see what our options are for premium services like commercial support. You know, the stuff we can't give away even if we wanted to because their are real costs involved which we couldn't subsidize without going bankrupt.

Note that we're probably not going to be using FPS in the near term but I did research it exhaustively before I ruled it out (for now). While it's fresh in my mind here's the summary for the benefit of those who might be considering it as an option.