I have a noob question. The stats on cloths is very confusing to me. For instance: If an article of clothing says +3 fire does that mean +3 defense from fire spells, or that spells you cast in the school of fire will get a +3 boost?
The listing is usually (except for some low level equipment) a percent boost to the base. If there's a school symbol there, then the boost only applies to spells in that school.
A purple-red dot: Accuracy boost by the listed percent.
A golden sun in a square: Power Pip chance boost by the listed percent. This is always global (not school-related).
A fist: Damage boost by the listed percent.
A shield: Damage reduction by the listed percent.
You can see what your total boosts are by pressing "C" and looking at the first tab.
A lot of people do take the equipment that gives the highest amounts of health and/or mana. These people want to minimize the chance of being defeated.
Others want as much power, accuracy, and damage as they can get. These people reason that the more powerful they are, the faster they'll destroy the enemy, and the less damage they'll end up taking.