>Most likely knew the lay out of the house
It is possible that he knew the layout of the house but there are no indications that he did and certainly that is insufficient to deem it to be "most likely".

There was sufficient ambient lighting, particularly with the aid of the Christmas tree lights and all those oft-repeated stories about a 'virtually secret room' that was 'hard to find' and the like have absolutely no basis in fact. Even those utter clods at the BPD found the room, they didn't open the door and look inside, but they found the room! And lets face it, them BPD-types ain't quite stellar in their abilities.