A navigator will be somewhat military, making sure you add the aquila. May I suggest a BDU look with some flak and a hat of some sort? I know thats vague as hell (sorry mind running a blank)
I would think they would have some computer/tech on them, like a pda built into a bracer, perhaps some eye mods? (bionics?) Those come to mind.
If your going to be an astropath, blind with a third eye, with robes would work.
And for the space wolf scout, best inspiration is the models, for them, bare muscular arms and big manes of hair, with beards aswell. Think vikings in carapace armour ^^
I hope some of that helps, as I always thought any military side of support, would wear the Cadian kind of fatigues with armour. Maybe look at the models in the Imperial Guard HQ section? The masters? (name escapes me)
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