How do you guys know all this stuff?
I was very curious, when I was in my teens and twenties. Still am, but I've since discovered that some things are better left alone.
And I've studied them academically, as a Catholic trying to learn more about Judaism, not as an occult "seeker."
A lot of medieval occult legends seem to derive from misreadings or fanciful elaborations of Talmudic, Zoharic and Heikhalotic Jewish texts.
Likewise a lot of very orthodox works of Catholic piety - like El Castillo Interior by St. Teresa of Avila (herself a descendant of Jewish converts to Catholicism) are closely paralleled in such literature.