Alois, Basile, and Malo are suitors of Justine's, who she brought down to her "dungeon" to have...well...sexy time with (or at least that's what I imagine happened.) and then she slipped absinthe into their wine, put the wheel around their necks, and when they told her that "her beauty is blinding", she gouged out their eyes and laughed at them. Thus, the three suitors are created. Their cells are located in the first jail area in the story, and upon entering them, sounds will play based on whose cell it was and what they did.

The people you save have nothing to do with the monsters. There are multiple ones because they are technically different people, and they do indeed have different sounds.

blinded them with hot irons held near the eyes (the nerves die well before the skin/structure does).