electrical - Basement stairs 3 way switch with 2 lights
I can't make sense of what you have going on but, the smoke detectors are simple black and white to each of them in the house and the red involved in the smokes is just a signal wire to turn them all on if one goes on. That being said the, aside from the line and neutral wire you can largely ignore the smoke detectors. And yes that picture is a 3 way switch.