#1. Your colleague more than likely damaged your rear caliper. As stated, you would need to turn them counter clockwise to compress them. The e-brake does use the rear pad for the braking mechanism which sounds to me that its not making full contact onto the rotor.

#2. Those screws your referring to need to be removed using an impact driver / screw driver. A regular driver will break the head off which in turn will require to be drilled out.

Honestly, replacing the pads and rotors on your car is super easy. Might seem challenging but not impossible.