UNIT - Creature Balance + Visual Changes

You've convinced me, now the question is about the Dwarf Priests:
Wall of Fire and area attack against 3 damage units and Fireball. I always took the former without hesitation.

Here, it depends on the character's build: if you have "Secrets of Light" and/or "Sar-Issa's Ring," then it makes sense to take the latter, but otherwise, I usually take the former as well.