1) You Cannot Use the Glory Kill to Recover your health.
2) The Level Design is just a big Empty Box and gets worse in the second stage when he summons 2 walls to funnel you into his rockets.
3) He's a god damn Bullet Sponge... I mean. Some enemies like the Mancubus & Barons are Sponges too but they can be murdered with one quick slice of the Chain Saw.