In order to get the maximum damage from fire and frost breath shouts and weapon enchantments along with the most charges on a weapon before it needs a soul gem recharge, is it this:
Destruction: 2/2 Augmented Flames & Frost Enchanting: 1/1 Fire & Frost Enchanter Enchantment: Fortify Destruction Destruction Skill: 100 (if not reducing cost to 0 via enchants)
The one im not totally sure on is the destruction skill / fortify giving me more charges on a weapon enchant. Assuming everything stacks and i have to enchant the weapon AFTER i take the perks and get the destruction skill up. Planning on using 2 fortify destruction enchants so i guess I'll need 100 destruction skill.
Soul Squeezer and Soul Siphon will help with charge maintenance. And the higher your School skill and the more cost redux you have, the more 'charges' your weapons will have if the enchantments are based on that school.
The enchantment with the greater effect dictates which school the weapon is governed by. You can adjust this be reducing the slider on one of the enchantments enough that the effect you want is the dominant one. You can tell this by the aura color of the weapon.