Are they Psyckers? I know they aren't technically, but for the purposes of ignoring a Navigator's abilities, if a creature can ignore a psycker's ability can they ignore a Navigator's?

As per my memory of RAW if you have any points in Psy rating then you are a Psyker.

Are Navigators Psykers ? p179 of the Core Rulebook,

'For all game purposes, Navigators are considered psykers."

Can you give me any info about the armor the navigators usually wear?
(The power armour like breastplate with tubes, and the robe decored with a lot of orbs.)
Does it have a specific name(like "Terminator" armor), stats, or a description why the navs are wearing it?

I mean this one.

Lengytam said:

That's probably just Xeno-Mesh Armour or a Light Enforcer Caparace. Tubes in 40K are mostly a cosmetical detail.