Yes a thermostat is required. No a ball python will not move from an overheating heat source. While this was caused by a heat rock, the same will happen with a heat mat.
https://ball-pythons.net/forums/show...cks-Just-don-t!
Your thermometer probe should go under the substrate on the floor of the enclosure because ball pythons will burrow to the heat.
Your thermostat probe should go between the heat mat and the underside of the enclosure so the snake can't move it off of the heat mat or pee on it, which could cause a false low reading to the thermostat.