That would work, yes.
Yes, it’s possible. You can place Trigger Boxes and have their Events fire when things overlap them - think area trap or a healing zone. Or a chicken coop that spawns chickens when the player enters.
edit:
Accessing framework classes (game mode, controller, character and so on) is pretty straightforward and can be done from pretty much anywhere, like so:
The other way round, sending information *to *the Level Blueprint, is a tad more complicated but can be done, too.