This style is so beautiful and broad. It really needs to be documented before it dies out. How many truly know as much as Sifu Joseph? More frightening is did Lee shing know even more and that knowledge is already lost?

You could learn the forms fairly quick but without understanding they are just a series of motions. To understand is a never ending process. Depends how well you want to comprehend the system before considering yourself proficient.

Depends on the teacher and style of wing chun. Some styles are as you said the bare bones and the head of the system doesn’t understand it. You could learn those in a couple of years and have nothing more to learn.