They are mounting holes, usually around the 2 - 3mm mark.

The roller switch is usually activated by a ramp fixed to the moving component. Vast overshoot is okay. It's more a limit sensor than a position sensor.

A button microswitch is much better than a lever if you want position. Simply add a bolt to physically stop the slide before it crushes the switch. Theoretically you stop before you hit the bolt :naughty: