Im also curious if all bonus to sorceries and/or magic damage is applied to each projectile in spells aswell.

This might seem a bit random. But do you know how much the Primal Glintstone Blade talisman reduces fp cost? Because if it is percentage based then the more costly spells benefit alot more from it.

If you want to do the math, pebble costs 7 and meteorite costs 36 to summon the starting 3 meteors, with additional being summoned the more you put into the spell but I am unaware of how much it is per FP. My FP is at a comfortable 148 and I counted 12 summoned above. If we deduce average, while 4 meteors did 3800 damage, to be nice to our magic haters lets say it did 800, no 700 per metoerite. 12x700 is 8400 damage. Pebble can be casted 21 times with my fp. Pebble did 341, 341 x 21 is 7161. Lets also ignore the range, AOE, stun potential and dps to make things much much more bias towards pebbles side and look at just FP/Damage ratio.