>>5208656 The light will function like, drawing inspiration again, Darkwood's lamps.
A room will be rolled for, and much like your flashlight beam exposes what's beneath the dark, a perpetual beam will layer over the room you roll. The process is automatic.
The flashlight, like everything including your weapons and JJ, are not immune to damage, and can be noticed if the enemies in question are intelligent enough to decide it's worth targeting. Not even the iconic, classic Gumball Machine is immune to being targeted.
If for whatever reason the power source (hereto unknown where it is) at Night is damaged, the light goes with it.