#1 and #2 certainly, and I'd say they felt more stiff than choppy. In particular, I think the fact that the main character animated the same no matter how fast your character was moving, or if your character was moving at all added to the stiff feeling.
The shadow monster didn't feel particularly dynamic because the sprites seemed to just constantly rotate in a circle at a fixed speed, as opposed to potentially slightly more varied movements.
I think you have a pretty significant choice to make in terms of the direction of your game. Do you want it to be a level based puzzler using possession mechanics, or do you want it to be more of a steeple chase, where you constantly are passing the torch?
I'd lean towards embracing the latter, simply because I think that one interaction has a lot of emotional impact that can potentially be built upon in tons of interesting and varied ways.
If you lean towards the puzzle genre, one potential mechanic that might work well could be to make the darkness only move when you do. That way, the player has time to think about their next move, but also has a constant impending sense of doom.