1.) No. Happiness is actually in equilibrium in my house. I never had affection drops. There is however a stronger affection decay this patch, 0.8.3.7; that decay is functionally stopped once your NPC reaches 116 Affection. That might be causing your affection drops and you attribute it to happiness when it's just the in-built mechanics
2.) I'm not complaining about my household. They are managed pretty well. More than well in fact. I just said there's a funny willpower drain for anyone below 30 willpower. And it is not tied to badfester. And that it might be affecting other people's accounts too.
3.) Without the unconscious training exploit, I do not think anyone can train a random NPC to be as good as a fully trained 0 exploits Cassius Bauer or Clea Vallas. Best you can do is create a dodge tank. Given the enemies of Aria's Rebellion, a dodge tank will excel vs the warmasters and possibly fall to the Bofors and the minigun enemies. Should still be doable however especially now that spells are a thing, NPCs can access level 2 health implants as opposed to only level 1 back then, and Vallas exists now to ensure the death of the 70/70 soak APC with her Liberator trait.