Some questions from a newbie

[Willburn]

Oh and by reading the boards I have figured out the + and - deducts or adds depending on your skill in that magic. But this as far as I know isnt mentioned in the manual. For example a theoretical spell with fatigue 5- how much will the fatigue be reduce by casting it with a mage with 3 skill. ( i know of the reduction metioned on page 86-87 but is the - part something else? I mean since some spells have it while others dont.)

And damage spells with + do they add 1 damage per 1 skill point above the spell required ?