I've compiled a list of all spells, and locations, for the three achievements. The second post after this will be a sort of how-to on the NPC and Covenant locations.
Fire Surge - Painted World Acid Surge - Painted World Great Chaos Fireball - Join Chaos Covenant Chaos Storm - Level 2 Chaos Covenant Chaos Fire Whip - Lost Izalith Flash Sweat - Laurentius Iron Flesh - Laurentius Combustion - Laurentius, Quelana Fire Orb - Laurentius, Quelana Fireball - Laurentius, Quelana Fire Whip - Quelana Great Combustion - Quelana Firestorm - Quelana Fire Tempest - Quelana Great Fireball - Quelana Undead Rapport - Quelana Power Within - Blight Town, under giant bug Poison Mist - Eingyi, or found in Blight Town Toxic Mist - Eingyi
Heal - Petrus/Rhea of Thorolund Great Heal - Excerpt Petrus/Rhea of Thorolund Seek Guidance - Petrus/Rhea of Thorolund Homeward - Petrus/Rhea of Thorolund Force - Petrus/Rhea of Thorolund Great Heal - Rhea of Thorolund Wrath of the Gods - Rhea of Thorolund Magic Barrier - Rhea, post Tomb of the Giants Replenishment - Rhea, post Tomb of the Giants Karmic Justice - Oswald of Carim (Come At Me Guy, in Belfry after first bell) Emit Force - Siegmeyer, after three knights in Anor Londo Sunlight Blade - Anor Londo, after Gwyn Lightning Spear - Warrior of Sunlight Covenant Great Lightning Spear - Warrior of Sunlight Covenant Darkmoon Blade - Blade of the Darkmoon Covenant Gravelord Sword Dance - Join Gravelord Servant Covenant Gravelord Greatsword Dance - Level 1 Gravelord Servant Great Magic Barrier - Ash Lake, second giant tree Vow of Silence - Painted World, top of Annex Soothing Sunlight - Duke's Archives, kill monsters near Logan's cell Bountiful Sunlight - Duke's Archives, kill monsters near Logan's cell Tranquil Walk of Peace - The Catacombs
Fall Control - Griggs Aural Decoy - Griggs Soul Spear - Griggs, Logan Great Soul Arrow - Griggs, Logan Great Heavy Soul Arrow - Griggs, Logan Homing Soulmass - Griggs, Logan Magic Weapon - Griggs, Logan Magic Shield - Griggs, Logan Soul Arrow - Griggs, Rickert, Logan. Default for Sorcerer. Heavy Soul Arrow - Griggs, Rickert, Logan Homing Crystal Soulmass - Logan Crystal Magic Weapon - Logan Crystal Soul Spear - Logan White Dragon Breath - Logan drop, after he's gone hollow Great Magic Weapon - Anor Londo Hush - Sen's Fortress Strong Magic Shield - Duke's Archive chest Hidden Weapon - Dusk of Oolacile Hidden Body - Dusk of Oolacile Repair - Dusk of Oolacile Cast Light - Dusk of Oolacile Chameleon - Dusk of Oolacile Remedy - Blight Town Resist Curse - Ingward
Chaos Covenant+Eingyi - After Quelaag, go below the bell level and find a false wall. Talk to the Egg Undead and answer "Yes" to move on. You do not need the Witch's Ring to join the covenant. After joining, Eingyi will sell his spells
Laurentius - Rescue from Butchers in Depths. He is in a barrel. Roll at it.
Quelana - Blight Town. With back to water wheel, she is sitting on the first pillar island to the right.
Petrus - The fat Way of the White guy at Firelink.
Rhea - The 'maiden' who shows up near Petrus later in the story.
Warrior of Sunlight Covenant - Requires 50 Faith to join. However, if you assist other players in killing bosses, the requirement drops by 5 for each assist.
Gravelord Covenant - MUST JOIN BEFORE TOMB OF THE GIANTS. Have Eye of Death. Proceed to the lower levels of The Catacombs. You will come upon a prowling-demon at the end of a long hallway. Immeditely in front of the prowling-demon is a slightly open coffin. Climb into the coffin and wait about 30 seconds. You do not have to kill the demon, but you must have at least one Eye of Death on you. A cut scene will trigger and you will be taken to Nito's tomb. Go and interact with the giant coffin containing Nito, and join the covenenant.
Griggs - Locked in the house in lower Undead Burg, before Capra. Requires buying Residence Key from male Undead Merchant.
Logan - Free from Sen's Fortress. Then Duke's Archives. He'll appear in a treasure room behind a bookcase afterward.
Dusk of Oolacile - After defeating the Hydra at Darkroot, proceed into the left side of the lake. Follow the wall all the way down to find a golden golem. Rusted Iron Ring recommended. After defeating it, this NPC appears. Her summon sign will appear next to the rock you probably used to cheap out Hydra.