Look in about:config if you haven't already, and take a grep through the source for the full list of settings that you can adjust. It is indeed disturbingly large and the majority of them aren't officially documented either.
Figuring out what they do is a different story, but at least that's one way to get a list of all of the possible ones.
It really is an insane situation. What is up with Firefox's stealth anti-privacy and spammy marketing features controlled by hidden, undocumented settings that are set to (violate privacy and spam me) by default?