×(1) requires all four constructs to trigger.
(2) requires three constructs to trigger from inside the room but only two from the outside area.
(3) requires three constructs to trigger from inside the room but only two from the outside area.
(4) requires only one construct to trigger, but it has to be positioned in a particular way, from the inside area.

From these assumptions, there's no way to plant constructs on (2) and (3) before I go outside, and if I leave two of them behind when I go outside, there's no way to get the last construct on (4) - it just sticks to the walls of the area uselessly.

×wrong. It can be easily done with 3.

×wrong. It can be done with less, but I would recommend using all 4 for this one.

×wrong. It only takes 2.

×correct. Abuse turn 30.

×Everything should be done by the time you drop the first trapdoor.

×Sometimes (several times) I forget I have a sword that can block things.