So, how exactly do adv. auras work? (and just auras in general)

also wondering, does super body or whatever its called effect the adv auras?
for example if i use adv dark and super body will that be 30% + 40% ?

It's 20+40 not 30+40, max Adv. Dark gives 20% and replaces Dark without stacking with it. When you have an Adv. skill with points in it and use that aura, the skill icon becomes the Adv. aura icon and you simply get the bonus as listed in the Adv. skill description.