Yeah. Using the ichor and mutations can boost you up really fast. There will be consequences for doing this, but right now there are no disadvantages, except for some NPCs not talking to you if you are a mutant and that can be negated by wearing the church robes.
Ghouls are great right now. New players hate them because they are really strong but as you said, they become a great xp resource later on. Future versions will have something similiar to a GTA wanted level. The more ghouls you kill, the more will spawn together with stronger variants.
I'm glad you enjoy the lore, even though there is not much of it yet.
Next update will have another part of the main story. You will go with the generals through a dungeon, meet Mr. White properly and give him the letter. Then you will have to chose which main character are you going to support. This means that I will remove the old condition for meeting Mr. White but he will still reward you for killing (And I will add more reward tiers). You will just have to do the main quest for that to happen.
I've got most of the tilesets complete. I still want to make some furniture and other bits, but the bulk of the work is done.
Also, killing Mr.White 20 times will give you some more lore and more importantly, a special name. If you start a new game and name your character in that way, you will get a secret alternate begining dialogue.