Well since only one of them is a combat NPC I would put those points into the appropriate weapon skill to boost hit chances. Either that or give them a super dodge skill so they last longer when people/beasties shoot at them.
the non combat NPC's are just fodder of sorts so again either boost their HP with strength skill or give them super awesome dodging ability.
Skills have no effect on builder/worker speeds so that would be pointless. Best bet at the moment is to increase stealth to hide from enemies, or the various HP enhancing stats for when NPCs can be shot at outside of Derra.
I've not heard of any skill requirements for NPCs for performing their duties such as construction, production etc in the pipeline so I wouldn't worry overly about that.