obvious answer i'm sure but just want some clarity.

You get an extra evade die when being attacked through and asteroid with a primary weapon.

Q. is this also true when being attacked by a missile?

sure it must be yes but just checking

let me just clear up another question at same time, again i think i know the answer but…

If shooting at a ship and your line of fire passes through two asteroids they still only get one extra evade, right?

Correct on both counts.