Locations One is located in Undead Parish. It is on an altar in the Undead Church (2nd section of Undead Parish), guarded by a big black knight with a mace. One is located in New Londo Ruins. It can be seen on the right hand when crossing the narrow wooden walkway. Three ghosts will spawn when getting near. One is located in Blighttown. In a wastewater pit, about halfway down from the Valley of Drakes entrance, guarded by fire-dogs and poisonous dart shooters. One is located in the Dukes' Archives. At the bottom of the prison tower, behind the octopus-headed monsters. Need a key that is acquired later in the level, lableled "Archive Tower Giant Cell Key". (Need to verify key name) One is obtained after killing Quelaag's Sister. Please note that you won't be able to join the Chaos Servant covenant or use the Bonfire in front of her anymore.
No idea how accurate this is since my guide isnt on me at the moment
Blighttown: upper area, close to the exit to valley of the drakes.
New Londo Ruins: past a narrow bridge next to the first two ghosts.
Dukes Archives: behind a large prison cell at the bottom(after dying from the first encounter with seath.)
Lautrec's world: invade it using the black eye orb--have to let him murder the flame keeper in firelink shrine.
since you get a firekeeper soul from lautrec (you essentially recapture the firekeeper's soul that he took), i assume you can kill other fire keepers and get firekeepers soul(i haven't yet tried as i'm not ready to move onto new game+).
Firekeeper Locations: Firelink Shrine: (behind a gate below the fire) Anor Londo: the very first fire you see has a lady dressed in gold armor. Quelagg's Domain: the chaos lady(spider-lady whatever).
keep in mind you have to have a firekeeper enhance your flask leading to a total of 4 looted from corpses and 3 from npcs meaning you can have +7 by new game+ (heals 800 according to the japanese wiki).