ok this is the low down.
the point of the holes. when the pads contact the rotors they emit a gas. under hard braking the gas builds up between the pad and the rotor and actually pushes the pad away from the rotor. I holes let the gas escape, and increases braking power. If you look performance brake pads have a slot cut in the center of the pad to do the same thing.
As for the slots. when repeated hard braking like when road course or auto cross racing. A pad can form glaze on the face of the pad from over heating. This is called brake fade. The slots are like razor blades. every time they pass over the pad they shave off a small layer of film off the pad. The problem is when used on the street it causes the pads to wear out faster. That's why you only see drilled rotors on cars from the factory.
This has been performance brake rotors 101.
thanks and have a nice day
2006 Mustang GT lots of mods ex wife has it
1979 corvette stingray #'s matching 47K org. miles
1970Chevelle SS 454 big block Old School 500hp Sold