Those are the other curiously unstated issue swith the Benghazi affair, as to why did someone do that, on the theory that tells you who did that.
That's most especially because it was not widely known that Ambassador Stevens was going to be in Benghazi in the first place, because the Embassy was apparently cased that morning, and because the attack itself wasn't a small one. That's very curious there, if the mice talk too.
"He then met with the City Council at a local hotel for dinner, an event at which local media invited by theCouncil showed up unexpectedly, despite U.S. efforts to keep the Ambassador’s program a nd movements from being publicized."
Given the gravity of the signal of killing an American ambassador, that's a signal that some might think has to be answered, in which when you look at its functionality, the why telling you the who, one thing stands out as to the question: Cui bono?
What stands out is that the attack most definitely made the position of those who favored toppling Gaddafi more difficult, like those who don't want to be toppled perhaps, and who have a history of doing such things?
Enemies sometimes work with enemies against worse enemies.
Of course, that in itself is a warning too to take very seriously as to toes being tread on in the Middle East right now, if sometimes then you have to stomp on them since to fail to do so might appear dangerously weak.