Do you have a Dremel? If so, chuck up a nice soft brass brush and run around that seal groove a few times scouring each side. You'll be surprised at the cloud of dried brake fluid you kick up from your nice clean caliper.
If that's not going back into service immediately, use a brake assembly lube instead of brake fluid to lube it on assembly.
WRT lube on the back of the pads, that is different stuff, must be high temp brake grease or antusqieal paste, use only the lightest smear between the antisqueal plate (if you have one) and the pad, and likewise, just a light smear on the side between the piston and the pad - only in the area that the piston bears on. A little is enough.