#3
Oscillation picking is like alternate picking in a circular motion to conserve the use of energy that normal back-and-forth motion uses.

Oscillation from fuzz is a sort of feedback, I think. Matt Bellamy does it from time to time with his fuzz factory (Plug in Baby intro, for example).
#4
Do you have any good guides to teach me?

and why is oscillation a good?

And what are the benefits of using hollowbody/semi hollows?

Thanks so much!