1) Given the massive amount of martial cross-pollination that went on, both from overseas and within the island chain itself, I think that mishmash would be the word.
2) Japanese regulated everything, and had records of it all
3) Okinawans didn't. Also, the martial arts weren't as regulated there. The concept of martial art as regulated tool of the state, which is VERY Japanese, didn't really show up in okinawa. Which means that many more people learned them. There was also much sharing between styles, especially around the relative boonies, as well as many trips to China.
4) You may have met more edumacated dancers than I, but the ones I've met and asked where they got the moves went, what? Martial arts? It's dance! What are you talking about? And yet there the moves were, right out of the kata...
I'd have trained with him,
and read his book, had he bothered to write one!