1 - To be so close? It really doesn’t matter for the player at the end.
2 - Depends if they are neutral or not.
3 - Yes.
4 - Hardly.
What happens is they are neutral to each other only when you are neutral with goblins, exactly to avoid they killing each other and triggering your campaigns. Lose your goblin diplomacy and they get angry with everyone again.
This direct comparison raises another question: Why do the goblins have that sexy green firepit, but the undead are stuck with their regular, boring, old orange torches?
Agreed. Maybe the Undead could have a pale bluish-purple as their Faction Flame colour
I have no idea why, but I have always associated this sort of colour with Undead…