As far as the World Between Worlds, in my head, this is what the Jedi connect to when they ‘see the future’. They aren’t really clairvoyant but are like the Emperor was, opening a portal to this World Between Worlds with their minds in which they can see or hear everything the way Ezra was able to.
That’s just in my own head but it makes some sense. As time went on, the Jedi lost the story of WHY they could see a version of the future, they just knew they could.