I don't think there is a comprehensive skill list, and opinion differs on some skills, depending on playstyle, etc. The topics below probably cover the majority of skills. You can always save before learning a skill, and reload if you don't care for it.
Poison Weapon is quite effective, but not nearly as overpowered as Frost on a weapon. I didn't use it, so am not sure if it would make things too easy, or not.
ARIC'S WARRIOR GUIDEArchery as a warrior - my thoughtsThe topic
sorta new, got a quick question contains some information on playing survivors.
Kaan's Mage GuidePlaying a mage character...Chasing Josie... techniques for defeating Josephine (spoilers)