Ok, obviously I didn't read the rules very well, hence my confusion. I thought that the score was only based on the final house, not on all the other houses combined. Oops!
As for the burial ground thingie, I've encountered that a few times, I think it only happens in that one house in Riverview if I'm not mistaken? And yes, a ghostbuster shows up and offers to get rid of the ghosts. It's not new to the game, in fact I nearly asked if the ghostbuster would count as an NPC in the previous challenge. lol