[Flatrater]

Do you have your owners manual handy? If you do read the subject on gasoline!! The owne's manual will state that a slight ping is normal!! Engines are designed to run lean for gas mileage reason and others. But on yuor engine you have knock sensors that monitor pinging and adjust the timing for it so it is normal to hear it, it is not normal to get a loud knock.

Try adding some brake fluid to your master cylinder, that will take care of your brake light. Have your brake system checked out for leaks and low pads.