I'm guessing #6 is referring to the Crushing Block card. Note that it has been clarified in the FAQ and can be played next to lots of things:
Q: Which map items count as obstacles for the Crushing Block trap card?
A: Crushing Block may never be played in a space adjacent to a pit or any token (or built-in map element) that blocks movement. The reason for this is to prevent the Overlord from sealing a hallway completely and preventing the heroes from ever progressing. This is a list of all relevant obstacles, current through the Road to Legend: Boulder, Crushing Wall, Rubble, Water.
