I convert my RS4 from 2007 with Ceramic brakes on rear axle for some year ago. My car have Ceramic on front from new, but I didnt like the steel at rear end.
Use disc, braket and pads from RS6, C6. Small modify of the bracket, make a thin spacer between disc and hub, and Mill some mm from all 4 pads.
I use the RS4 standard calipers, so handbrake works like standard. Brake shield I dont remenber, but it was from some RS model.
Use my car daily, and 2-4 trackdays every year. It works without problem.
The only negative is brakepower is little to strong in rear end, you can feel it when braking from high speed.