In what order to different buffs apply?

[InDarkestNight]

I was planning on trying to use a fury spell on Keeper Carcette. The problem is she de-spawns (for lack of a better term) at level 10, and she has a minimum level of 15. This means that there's no way I can acquire the frenzy spell before she disappears (you have to be at least level 23 for it to spawn in treasure chests, or have your illusion at 40). This means that I'll have to do this with the base fury spell, which can only affect targets up to level 6!

Doing research, I could get the dual-casting perk before level 10 easily. Dual-casting fury would push its level cap up to 13. That still isn't high enough, so I need another buff. I can get that either through a fortify illusion potion, or worst case scenario I can become a vampire.

I would guess this would be sufficient to push the level cap for fury to at least 15. However, this has left me wondering; how do buffs actually stack in this game? The only thing I've ever heard of is if you have both magic resist and spell absorption, the damage will be reduced by the magic resist first before the game checks to see if the spell absorption fired.

How do all the various buff stacks? Annoyingly, many of them increase values by percentages. For instance, the smithing skill increases your tempering by a percentage based on your skill level, and its perks add anothere percentage on top of that, then you have fortify smithing enchants and potions, the ancient knowledge buff, seeker of strength, you get the idea. Obviously, the exact amount most buffs will actually give you will depend on the order in which they're calculated. What is the actual order? For instance, if you dual-casted fury as a vampire, what would be its level cap? How do all the various 'fortify skill' effects stack? What about skill level and perks that boost your effectiveness further?