As below. How to make actor not to trigger traps via script?

I think I have seen some follower mods that can do that so it seems its possible.

Add the Perk that stops you from activating traps to the NPC.

Just remember that this has to be done via the CK, not via script. Unlike the player, NPCs ignore perks added to them during gameplay.

Does faction ownership have any effect, say on a rune or soul-gem trap?

if the ownership of the trap is set to Draugr faction, will draugr not set the trap off?