the first link is about modifying a system's c compiler which the op's tails live usb is infact a solution to
the second is about altering firmware on harddrives, which is an engrossing writeup, thank you, but does fall short of suggesting ways to identify and remedy such an invasion
your third one is about intel's ME which i figured i'd see someone link to
unfortunately, the really interesting listed elements in my original post are the preventative and resolutive elements