The spice must flow.

Is the spice salt? Because I'm tasting some.

He is referencing dune, the novel.

No idea what you are talking about. I was making a reference to a famous set of novels with giant worms on a desert planet central to the plot.

Here comes my favourite character
NICHOLAS D. WOLFWOOD

Why does Knives want to open Vash's gate? What even is this gate?

Me who say EP 9 aaaah well its big oh no for normal people

Is it some kind of black hole/planet killer?

Well it may be one of those sorts XD