3) Is there any way I can set the enemy keeper AI or prevent it from being overly expansionist and not making a total mess of it's starting dungeon? I know the AI usually ends up doing this often in many maps, but the problem is that the moment you destroy the hero heart the walls all turn to earth and the AI immediately digs through it to start claiming territory. I want it to be the other way around, it's the player who has to go knocking on his door.
AI Keepers will not dig anything; they only dig for rooms, to attack, and all along any rock.

If you want a player to get to a clean AI keepers wall, there are several strategies to achieve this.
Some examples:
1. Use rock instead of walls. The AI will surely dig along he edges of any rock though.
2. Use walls from another keeper, with one claimed tile of that keeper behind it. It can not dig that, and your player can dig there safely, until it claims the tiles. This trick is used in lots of custom levels.
3. Use the keepers wall around water or lava, where the AI keeper can not build a bridge. AI Keepers will not dig these walls, until a bridge is researched, or build there by another. I would do that in my map Controlled Demolition, and never saw the AI keeper dig that wall, until a bridge was build, while testing. Although there even was one tile beyond the wall to the lava. Big enough rooms would touch all off the wall there though; AI may still dig for it's own designed room, if free room is 3 or more tiles.