Questions on splash damage

What item rolls impact splash damage generated from a gun? Weapon damage? Area-of-effect damage? Gun specific (SMG, etc.) damage? Manufacturer damage?

How does crit damage work? How does splash determine a crit? To stat rolls on class mods multiply crit damage?

It works exactly like a crit with any other weapon – if you hit the crit spot with the projectile it’s a crit and crit damage is calculated the same way. If you don’t, it’s a regular hit.

If you hit an enemy’s crit spot and the splash damage damages other enemies too, the first one receives crit dmg and the others receive normal damage because for a crit the enemy needs to be hit in the crit spot by the projectile.