Guilty. (Just wrote this and lost it so here goes again).
Spellcaster Classes (Primarily) = Brotherhood Wizard*, Bautarian Herbwarden*, Dessi Magician* & Vakeros Warrior-mage** ALL have combined stats of 41+(3x Random Number).
*5+RN CS, 16+RN EP, 20+RN WP.
**10+RN CS, 16+RN EP, 15+RN WP.
[Grey Star, a Shianti Sorcerer - like a Dessi Mage, has 10+RN CS, 20+RN EP & 20+RN WP but he is directly taught from a baby by all the Shianti, bar one.]
Kloon Sage* has Willpower but combined stats of 36+(3x Random Number), versatility making up for lower stats.
*6+RN CS, 20+RN EP, 10+RN WP.
All other classes (I think) do not have a Willpower score. So you could keep them in line with the Kloon's stats in total; 36+(3x Random Number):
Willpower = 6+ Random Number - Kai, Ranger, Buccaneer, Telchos Warrior or any versatile Warrior Class.
Willpower = 4+ Random Number - Knight (Any) or other primarily Warrior Class.
Willpower = 1+ Random Number - Dwarven Gunner, Ice Barbarian or other strongly non-magical Warrior Class.
As for uses of Willpower - any ability of mainly Magical or Psychic nature that costs EP may be paid for with Willpower instead, including Magical Items like Helshezag. Lone Wolf would gain a much better benfit with Psi-Surge in this way {e.g. vs Chaos Master!} and Kai Grand Masters would be more likely to use Kai Blast too.
Restoring Willpower -
Potions to restore Willpower would cost the same as the EP equivalent.
Decent night's sleep (8 Hrs): 1EP or 1WP for a undisturbed/peaceful sleep (not on guard), 2EP or 2WP or 1EP & 1WP for a deep, comfortable sleep.