It would be against the law for a motor manufacturer to fit a light which could cause the brakes to fail.
It is the brakes light switch
no
The brake pads are worn out and need to be replaced. The grinding sound means your brakes are about to stop working.
when the old ones stop working
Yes and any and all cars brakes get stiff or stop working when they wear out
A problem with your anti-lock braking system. Your brakes and your ABS are two different issues. Your ABS system keeps your brakes from locking when coming to a hard stop. If it is not working correctly your light will come on. Best to have a shop look at it.
Anything that brings the car to a complete stop? Such as the brakes or a Tree?
I step on brakes, dashboard light comes on which says stop.
It means there is a problem with the anti-lock braking system. If the light is on, The system is not working. What this means is that in an emergency panic stop where you stomp on the brakes, the front wheels will lock and the car will slide forward instead of coming to a safe controlled stop.
Brake Booster needs replaceing
The bulb could be 'blown'. Remove the working bulb from the other light and try it in the socket of the one that isn't working.
Check that the cruise control module fuses are not blown in the fuse panel. Also make sure your stop lights are working; cruise controls are designed to disengage when the brakes are applied, and one method of sensing that is to monitor brake light current.