So with regards to your question, "How should he be looked at as far as TKD History?", he should be looked at as the instructor of a number of the Kwan founders and as such, an indirect contributor. The same way that Takeda is viewed as Choi's instructor.
I am well aware of the controversy regarding DRAJ and HKD; I'm not dredging that up, but the fact is that HKD practitioners recognize him as Choi's teacher and don't see any conflict; Choi taught what he taught and the art evolved as it grew. TKD with Funakoshi should be no different.
Good question. As a person with a KKW rank, I'm going to say no, and instead say that without General Choi, we have no Taekwondo (regardless of how you break up the syllables). A lot of what drove the TKD movement was political, not technical, and General Choi was definitely a prime mover. Without him, it would not be called taekwondo. Probably taesoodo, kwon beop, or maybe even taekkyeon.
I think that regardless of what the donor art was that that served as the platform, you would have ended up with WTF sparring, and there were enough CMA practitioners in Korea to put a new MA with high kicks together without the contribution of karate.
Had TKD not taken off, HKD might have been the focus of unification.
We would have still ended up with WTF sparring? Interesting!