Back from RL stuff, so i'll get us moving again. To answer your questions: Not all of the people were dead. Some were simply not in town at the time of the massacre, and others are newer arrivals or people who are not quite dead, and still more took deals similar to your characters - resurrection in exchange for a tithe of their own souls. Streban is all about the souls - it's his fuel and his power source (and part of the reason why he takes issue with demons, who also want souls).