Covering the brake is putting your foot over the brake pedal without touching it. Riding the brake is actually putting pressure on the brake pedal.
Holding your foot just above the brake pedal, In case you need to brake.
Hovering your foot over the brake without actually pressing on the brake
Somebody who "rides" the brake is constantly applying pressure to the brake pedal with their foot. People who tailgate ride their brake alot. "Covering" the brake is a form of defensive driving. For example, while proceeding through a traffic light, you would want to take your foot off of the gas pedal and place it just above the brake pedal (without applying pressure) to decrease your reaction time in case you need to brake suddenly.
Its called "covering"
Hovering your foot over the brake without actually pressing on the brake
Covering the brake
you have to take off the panel that is covering around the brake and then you will see the brake light switch on the front side of the brake you can just simply turn it left or right and that will adjust it
ABS brakes should have no effect on engine idle, but a bad power brake vacuum booster would have an effect on engine idle.
50%
None whatsoever. I would recommend you remove enough to get it down to the full mark.
Since most brake/turn use the same filament in the bulb(1157) then if the turn signal switch is bad or offset then it will effect the brake lights.