NPC traits used to have no impact on party's strategic behavior like raiding, while some impacted their tactical behavior like avoiding/going into hard battles.
Well, not that much related to terrain/area lately (1.57 btw)
I don't have upgraded since 1.57, and I remember having seen very strange production from imperial breeding villages too as @R1919.
No, Heroes party's skill/perk works in Bannerlord whatever their actual status while they still in the party.
Welcome in the Magic Financial World ? ^^