How much should brake pads rub?

I've finally gave in and changed my own brakes on my 95 Ford Taurus.
Changed the rear rotors and pads (ABS). Right side pads worn down to metal and left side had plenty of pad. Caliper piston on right side siezed so I brought it to a mechanic to re-seat it flush but it was very, very difficult to move (he said it ideally should be replaced) I managed to re-seat left caliper piston without too, too much trouble but did find one of the glider pins on the left anchor plate had siezed up.
Now to my question(s) - being that this is my first brake job and considering the very uneven pad wear and reusing an "unsiezed" caliper,
I'm not certain how much drag/resistence should exist when I turn the rotor or the wheel after it's remounted - there is more way more "grab" than I think there should be. Are the pads always supposed to stay in contact with rotors and if so how much? Emergency brakes seem to have correct tension, but is it possible they need adjusting if drag excessive?

Thanks - D. Cervoni

I agree, replace the parts and replace anything that is doubtful.
In this case, that means rebuilt calipers and all new hardware. You will still be way ahead moneywise and you won't have to think about the rear brakes for another 100K miles.

Rex in Fort Worth