My brakes are making horrible noises so i know i need to change the pads. Do i need to change front and back together every time or is ok to just do the front? and should i get OEM pads or other?

 

Typically the front pads will wear before the rears, you should only need to change the pair (front or rear) that is worn . The OEM ones are okay, but they are pretty expensive a good aftermarket pad can stop better and they cost less than the OEM Brembo pads.