1) As I was experimenting, I discovered the hibox placed in the necklace, which was a bit counter-intuitive (usually it is in the visual center of the sprite, to make it easier to control the position by using peripheral vision only)
2) Yeah, I was hoping to use that penalty for precise positioning and pixel dodging during the boss fight, but couldn't do that most of the time as it still was too fast (but that's my own problem)