About the Non-Stacking buffs part, From what I've seen, having triple (or double) lightning mains with anbu corps seems to stack, at least the leech part does not sure about the damage portion. Might be wrong but thats what I thought

Speaking of people dying, which buffs are carried over if certain ninjas were revived? Example, Orochimaru has a buff that increments for every death on the battlefield. If say Orochimaru has a 30% buff from his passive but then dies, and revives, does he carry on that 30% buff or does it get reset? Same thing with pretty much every scaling ninja (E.g. Roshi, Hebihime, Kimimaru.. etc)