It would have been helpful to have divided this great wall of text into smaller sections, to make commentary easier, but anyway...
I'll address a few of your points.
I have not read nor followed this thread about SA's involvement in 9/11. I intend to study the matter further. However, from the little I know/heard/read it appears to me that SA was involved. The issues for me is what part of the kingdom "sponsored/support" the 9/11 attack but more importantly ... why? What did they want to achieve?
My hunch is that it will be difficult to find documents/evidence. Any.. I will SPECULATE.
Not a promising start.
'My theory is based on minimal knowledge, and will be essentially impossible to substantiate'.
Nice.
SA is a wahabi (fundamental) Islamic state.
Um. Yes and no. The Wahhabis have control over religion: the Sauds have political power. This was agreed in a treaty in 1744.
The kingdom likely have competing (for power) factions.
This is very vague. Do you mean within the Al Saud family, within Wahhabism, between the various tribes, or something else?
What effect do you think this had with regard to 9/11?
Wahabism seeks to expand Islam throughout the world by violent conflict.... holy wars.
I'm not sure this is true at all. Do you have a source for this?
This is true for the Taliban, and AQ.
The Taliban are not Wahhabis: they are Deobandis.
Apparently in that branch of Islam... all wars against infidels are "good". I don't suspect that their war is organized under one central "command". All know who the enemies are.
Again, this is a very speculative claim. Parts of that are definitely untrue: the splits between ISIS and AQ, and ISIS and the Taliban, and ISIS and Boko Haram are real, and often violent.
Takfiri doctrine is by no means universally accepted, either.
I'm going to leave that there, but I think I've made my point: speculating in this way from a position of a lack of knowledge is unwise. I suggest you do some reading first. I'm not being patronising: this is an enormous and complicated subject, and it takes time to get even a basic level of understanding. I'm not saying I have that either, but I do have enough to be able to question your narrative here.