This is my guess based on what I’ve read and putting on the tin foil hat...
-Stevens was a loose end. He knew about this administration funneling weapons and money to terrorists in Syria and elsewhere.
-The election looked like it was going bad and they didn’t trust Stevens to keep his mouth shut.
-The video was preset as their cover story
-Protests were stoked by Code Pink and possibly CIA officials in other countries to validate the cover story
-Ambassador was supposed to be unguarded and his security forces were to ‘run away’ when it happened leaving him an easy target. It wouldn’t need to look like an all-out assault under these circumstances
-The Seals got wind of what was going down and intervened and it all went to hell requiring the terrorists to track down the safehouse and attack.
-The drone was overhead because they knew it was coming and were watching to make sure it went down as planned.
-They had no contingency for the Seals intervening so they went with the cover story and hoped it would stick
-They never expected calls for aid or for this to last 7 hours and have been in cover mode praying it would not be investigated.
Just my thoughts.
My Naval Colleges totally concur with you assumptions. They had to take out the loose-lipped bagman. All amateurs . Spiraling lie upon lie. Face the facts, Obama is sponsoring the brotherhoods jihad, forging together the caliphate.