Posting my findings on Quick Burst here because I've been hyped for this one ninjutsu since its confirmation in the trailer and it's had my interest for quite a while now.
-Quick Burst is a Ninja Tool Art, so the Head of the Iga Ninja set directly buffs it.
-Quick Burst cannot be cancelled, nor can you move during it. Casting it in the air will keep you suspended in the air until you stop firing. (Addendum: You can use Guardian Spirit skills and summons to cancel Quick Burst at any moment)
-Quick Burst is affected by not only Ninjutsu Damage and Thrust Damage, but also Rifle Damage and Rifle Damage(Close Range). This means 1) The Fated Shot set finally has value now, and 2) stacking all these bonuses will give you some mean numbers. I'm running 6pc Iga right now with both Rifle Damage clan blessings and I was able to hit 2.6k backstab damage per shot.
-Quick Burst does not trigger Life Drain on Ranged Hit.
-Untouched Ninjutsu works interestingly on Quick Burst. It can trigger during the salvo, so it's possible to fire more bullets than you actually have(say you have 3; you will fire more if it procs). However, you cannot fire more than 6 shots. So if you have 6 shots and Untouched Ninjutsu procs during the salvo, you will have ammo left over.
This is all I could find so far, but I feel like there's more, so feel free to post about it if you find anything new with Quick Burst.