Question 1
(Not entirely sure I understood correctly where you are stuck, but I assume you're in the top room of the tower)
You might want to check the room that's on fire for a certain item.
Also, what you look for isn't there. Look at the attachment for a hint.

Question 2
You have to rush to the back of the main room, where you can hide from the gas behind a small wall. Take a pause there and regen. Next, quickly jump on the wooden platform situated in the center of the room, where the boss is standing. Start smacking him and simply follow him when he runs.