do the brakes piston's in the rear push in, or twist in?

If the parking brake lever is built into the back of the caliper, the tool is used to screw the pistons in. That's common on GMs and Fords and some imports. If the parking brake is a drum brake inside the rotor, you should be able to push the pistons in by prying with a large screwdriver between the pad and rotor before you lift the caliper off its mount. That's common on Chryslers. If you MUST use the dreaded c-clamp to get a piston to move, it is sticking and the caliper should be replaced.

Just to add to this one they screw in.