That’s correct, cheers DC. The red grease is the stuff for caliper seals and pistons, Copaslip is for the back of brake pads and pad retaining pins.
Given the time and effort required, I think that Majdisast’s best option would be the 4-piston calipers from the later E-model (if they’ll fit). Not the cheapest way to do it, but the end result would be better brakes.