Thanks for doing all that work, and welcome. We certainly need better information about this episode.
I think that Stevens was not the primary target of the enemy military operations in Benghazi that night, and that he probably died of smoke inhalation while locked in the “safe room”. The so-called “safe room” looks on video like it was secured by the “rape gates” that are so prevalent wherever whites live in Africa. This secures persons against physical contact assault very well, but provides no protection from projectile damage (there is no evidence Stevens was shot) or (obviously) from toxic inhalation.
The objective of the enemy forces was, I believe, to reduce the so-called “annex” (which wasn’t annexed to anything) and to gain access to whatever was in the warehouse building at that location. The attack on the so-called “consulate” (which wasn’t one) was a successful diversion to draw attention and security away from the target, which it did.
The diversionary forces were not expecting a robust defense, and got bogged down by a firefight which resulted in the fire that killed Stevens, and Smith.
In addition to the details of who moved Stevens where, and when, we really need to know what was in that “warehouse”, who took it, where they went, and why they wanted it.
Apart from a possible arms cache and cash stocks this is what I have thought from the beginning was prize enough to carry out the assault...
Sacking of Benghazi consulate “a catastrophic intelligence loss”
He was the primary target at the "Consulate location" that is a given based on what was said by the terrorists. They specifically mentioned "the American".
"...he probably died of smoke inhalation while locked in the “safe room”."
He left the safe room. If he was there they would have found him. Yes the Ambassador most likely died of smoke inhalation--the CO levels would have been very high. His wounds were post mortem--no blood pressure means no bleeding. The safe haven area also had outer wooden doors go look at the FNC video again. The terrorists broke in past those wooden doors which had decorative windows in the top which let the smoke in. If instead of wooden doors with pretty windows, we had installed steel doors with an old fashioned horizontal locking bar on the back, they would have likely survived.
I can't really comment on the rest as I have not spent much time on the annex though I did do extensive internet searches for videos and photos with no luck.