[Kobal2]

For the spell fatigue question: the manual lists the fatigue formula as:

Casting fatigue = spell's fatigue cost * 1/1+Caster's path-spell path + spellcasting encumbrance

So an F4 mage casting an F2 fireball is only getting 1/3rd of the fatigue, not 1/2. 7, not 10.
Spellcasting encumbrance = natural encumbrance + old age penalty + armour encumbrance*2. This goes even for undead & constructs who do not normally get fatigued !

So a spellcasting SC needs as little armour as possible, and enough reinvigoration items to offset the fatigue of the spell(s) he'll be spamming. Encumbrance 0 shields like Gleaming Gold or Vine are a must (you can equip two shields and get twice the defense bonus/arrow deflection).

Unless he can cast Soul Vortex before wading into chaff then cast point blank AoE spells and the like, in which case the Vortex should take care of any incurred fatigue and the guy can think about wearing heavier armour.