Ok. I beat BH about a few years ago, here is how it works.
In heaven sky, You see a blue pentagon on the two headed dragon. hit it with bombs so it flickers red. Keep doing this and eventually you kill him.
No, you can't kill the ghost bomber.
Well, if you mean Garaden star, the final boss is lord Bagular.
If you mean the secret world, it's the evil bomber.
To spoil your nitros thing, look here. you do fight nitros on garaden, then he says to you that his mind was erased and garaden controlled him. he leaves the planet, giving you half his power.
peeling fun off a tree!