It isnt harmful to drive with a bad sensor, but you might notice the car steers when you step on the brakes and you will not stop as quickly.. so it is best to pull the abs fuse (you can look it up in your owners manual, im not sure what it is), it is located where all of the other fuses are on behind the driver door jam or whatever its called.
The sound you are hearing is the abs hydraulic pump turning on (the hum), and the pulsing feel and sound is caused by valves rapidly opening and closing in the abs pump. The pump creates the same force as you pumping on the brakes, and the valves are to control what wheels receive brake pressure (similar to someone pumping the brakes, except more precise and rapid). ( http://auto.howstuffworks.com/auto-p...lock-brake.htm
) Pulling the fuse is your best option until you fix it, but you should remember that when you press the brakes hard enough, they will act as they would in an older car. They will lock up and be disproportional and cause you to fish tail and prevent you from steering if the wheels lock up since there is no abs control any longer. Pulling the abs fuse will also cause a flashing brake light and solid abs light on your dash.
By the way when you say noise and vibration, if you mean the entire car and not just the brake pedal vibrates, you have a problem with the regular brake system. And if noise you mean a screech or loud rubbing sound of some kind it also is not the abs system but rather the regular brake system. This would be something to be concerned about and is not fault of the abs system.