Can enemies move through unexplored tiles to get to your character or are they stuck in the nearest known tile space until a character explores a tile that connects to them? If they can move through unexplored tiles, I’m assuming the whole tile counts as one move since that tile’s spaces aren’t revealed yet?
They do move through unexplored tiles, one space per tile. Note also you cannot attack them from range while they are on an unexplored tile. If you explore the tile, you chose which space they go in.
When you use SPECIAL markers for a test or during a fight, are they used up and returned to the pool of markers or do you permanently keep them once earned?
They are permanent.