how does sukuna use fire

Sukuna does die in the manga. The way it happens is quite dramatic and ties in with many other elements of the story, adding depth and tension to the overall narrative.

Sukuna typically has ten fingers in the manga.

Sukuna usually has ten fingers, just like a normal person. But in some special scenes or forms, it might vary.

Well, in the manga, Sukuna is depicted with the normal number of fingers, which is ten. This is consistent with the typical human anatomy.

No, Sukuna doesn't kill Gojo in the manga.

No, Sukuna doesn't kill Gojo in the manga. Their battles are intense but Gojo survives.

I'm not sure exactly, but you might want to check the latest chapters for the most accurate count.

There are fanfictions where Naruto uses the black fire after making a pact with a powerful entity. This entity could have granted him the ability to use the black fire. He may use it in a strategic way during battles, like surrounding his opponents with walls of black fire to trap them.

No, Killua doesn't use fire in the manga. His abilities are focused on other aspects like speed and electricity manipulation.

In the manga, Sukuna doesn't possess all 20 fingers. There are specific story arcs and events where his finger count changes based on the plot developments.