If you are riding around with your Ebrake up. 2. Caliper won't open and should be replaced or rebuild. 4. Replace disk as well cause there garbage turning them might save you 10 bucks each better to replace. Finally Good luck
That's all assuming that it isn't the brake pad shim; that little tin piece that holds your brakes still while in the caliper. It shouldn't be this because you would hear it as well. If this is a first gen tune in for I'm changing rear pads and rotors this month.
If not like the other guys said your the caliper may be down prematurely as a result of a faulty manual brake. That's happened to me as well. It's rare but it can happen.