[GATORB8]

Ceramic pads are lower dust but don't stop as well as semi metallic until they heat up.

It looks like there is just one sensor per axle per realOEM.com (front is left side).

Some tools to have:
Jack (jack pad for BMW), Jackstands, Torque Wrench, Breaker-bar/Lug Wrench, Socket matching wheel lug bolts, keyed wheel lock socket (if required), wheel bolt alignment tool/hanger (optional), Brake Cleaner and rags (clean the new rotors before installing), rubber mallet for freeing seized rotors, matching socket/bit for rotor retaining screw, matching sockets for caliper bolts and caliper bracket bolts, caliper piston press (or c-clamp with old pad), brake pad anti-squeal grease, gloves.

You could flush the brake fluid at the same time if it's been a while.

It's not that tough, just make sure you have everything you need before starting, and take your time.