Regarding Lee's martial art skills,
Reagarding his martial art skills, I can explain because I am Korean.
Actually I have seen him as an actor from mid 1990s. His muscle strength is so great so that he never lost in arm wrestling with any body in his life.
That's what I heard from the interview in the Korean TV entertainment program
As I know, he has leraned several martial art like Taekowndo, Kickboxing, etc.
Even he has an experience in having beaten several guys(I am not shure they are gansters) who tried to futzed him as he looks weak in bars or other places.
He is actually good at fighting. It is true.
But he never strives to show off his skills because he knows it could hurt someone.
That's what I know.