Last time I looked it was a maze trying to figure out FF extensions. A painful long learning curve. I wrote my first chrome/safari extension about 5 mins after I read the intro.
I'm currently working on completely redoing the Developer Hub to make it dead simple. Shoot me an email (gkoberger at mozilla dot com) if you have any suggestions or things that were particularly painful.
Grrrrrrrrrrrrrrrrrrrr - I'm still furious if I remember the days and nights wasted with false or outdated documentation.
At the end we skipped using FF (our original favorite) for these internal tasks and went along with Chrome - sadly to say so but this is currently broken with FF and great if that changes.