Great guide! I'm currently playing a Paladin on Hard.
A couple of comments:
Scouting isn't that important because you can just quick save before a fight and see what the stack has.
As for the anti-undead or anti-demon skills, they aren't all that bad in my opinion. These skills allow you to fight stacks stronger than your army.
Is Inquisition that bad? Thankfully I haven't invested too much into that yet (only went down to Runic Stone on the Mind tree).
I'd also like to say that I think you're selling the Paladin a bit short. His greatest strength I think is that he starts with a Resurrection scroll. I'm abusing the hell out of the spell right now and it's a great life saver.