Questions about spells 'n such

Hello again!

I have a few questions regarding spells and the mechanics of said spells.

1: Is there any difference between a stat-modifier like Protect Up effect granted by a consumable vs. Spell? Duration, effectiveness, etc?

2: Are stat-up/down spells and sabers based on a flat, unalterable number or percentage? 

3: Reisz Class info says that her Luck stat impacts the bonus damage of her spells, yet she only has stat-up/down spells and her summon series, which the excel sheet says deals damage based off her PIE stat. Likewise, Hawk has a similar set-up where his spells say their damage is based off his AGI stat in excel, but the Class info says his bonus damage is based off INT. Could you clear this up for me? 

Thanks!

1: They are the exact same.
Only one effect even has a duration: Transshape.
Every other spell effect works until dispelled/cured, overwritten (e.g. different saber), battle end, screen transition or death.

2: the percentages are flat, not affected by any stat. Power Up is a 25% increase no matter if the target is a fresh lv1 character or a veteran lv99 final boss slayer.

3: You have always two stats that affect spell damage, a primary/main and a secondary.
The main stat gives the biggest bulk of the damage, this one depends on the spell used, PIE for Lise's summon.
The secondary has a lesser impact (about a third?) and depends on the character, Luck for Lise.

This - along with variable cast speed by stat - was mostly done to avoid having a caster only need one stat and a physical attacker needing everything.
E.g. Duelist Duran needs STR to hit hard, AGL to hit more often (and harder with Lv1 techs), INT to get more damage from Lv2/3 techs and luck for more and harder crits; VIT and PIE for defenses as well.
In comparison Necromancer Charlie needed VIT for defense and PIE for magic defense and all spell damage. Ok, and INT for MP. That's it.
See the problem?
Now she needs AGL as well to cast faster and luck for some bonus damage. So 5/6 stats give her something useful now.

Satisfactory answers all around. Thanks for your swift reply!