The levers were supposed to turn off the vents, which stop you from floating after possessing an enemy. I found some bugs with them after submitting the game.
As for the damage you're taking, it's because you're touching the enemies. I realize now that I made the hitbox too small, which makes it nearly impossible to possess them safely. While I was developing, I could possess them without taking damage, so I didn't notice the issue in time.
I know I should have fixed that. Thank you so much for playing, and I'm really glad you enjoyed it!