Your concentration may be even higher than 65%. If they just drained the radiator, you still had the original 50/50 mix sitting in the block and heater core that didn’t drain out. I would get a refractometer and double check it. Drain a liter, fill with distilled. Recheck and adjust accordingly.

They’re going to have different valving. Replace both or replace this one with the same as the other side.

Press your brakes hard several times, then open the bleeder on the rear right. Some fluid may come out. If fluid sprays out, I’d suspect a hose. If it doesnt, you can most likely rule that out. Check the position of the barking brake lever on the caliper in comparison to the left side. If they’re in the same position you can rule out parking brake. If they’re in different positions, and the cable is tight, it may be the parking brake. If the cable is loose, it’s the caliper. If all those check out ok, I’d replace the caliper.