You don't have to fight the guy with the gattling gun but if you kill him (be prepared for an irritating fight) it'll make traveling the area a lot easier if you want to farm echoes or go inside the building to the right and pick up a new weapon and some armor. After you beat Blood Starved Beast you go to Cathedral Ward to fight Vicar Amelia.Breh, at this point I'm just trying understand where I'm supposed to be going period. I beat the boss with Alfred, it dropped a Chalice and I got Lamp inside the Church. It's a dead end after beating that boss so I'm confused if there's something I missed.
I just beat the big dude in the Dungeon, and unlocked a door. Right now, I'm backtracking about to fight the breh with the Gatling gun and I don't even know if that's what I'm supposed to be doing