Amnesia is a great game because their engine was designed explicitly for that style of game. The physics engine in particular is FAR from what FPSC uses.
That aside, to answer your questions... don't know how to help with the lantern, because that doesn't seem to be a question.
You can have character entities "interact" with a door. It would be similar to how the AI currently opens nearby doors by activating them, except instead of directly opening them, you would want to have the AI target the door, rotate to it, play some bashing animations, etc, then have the door open.
Hope that made sense and helps you out.
The one and only,
Only those who sow the seeds of their desires will reap their benefits later.
However, I have seeds of my own to tend to. I don't have time to be someone else's watering can.