Caliper piston turn in to collapse back inside, or does it go back with pressure

Yes, it must be turned to retract. There are special tools to do this, but sometimes you can use needle nose pliers in the slots on the piston and push in as you turn clockwise. There are small pins on theinboard pads, be surethey line up with the slot on the piston, this alignment is what makes it all work (e-brake). You only need to retract the piston enough to get the caliper to set down over the pads, doesnt have to be all the way in

Hi sgtmajor,

No, it means the slider bolts are stiff and requires to be lubricated.

If the left piston can be turned, you need to apply a little pressure to push it back while turning. Check if the handbrake cable has enough freeplay.

Sometiems they wont retract without the proper tool to apply enough torque to turn it. Opening the bleeder may help, but not likely. See if local auto parts store has a tool rental program or even an inexpensive version of what you need, If you are going to have the car for a while it may be a good investment. Also as mentioned previously, be sure the caliper slides move freely and are lubed