How easy are the wheels supposed to turn when the car's jacked up? Mine don't spin very freely at all. There's no heat, noise, etc. to indicate that the rear brakes are dragging, but I've heard there might not be.

I can't seem to perform any amount of adjustment at the brake lever that results in reduced drag at the rear wheels. Can anyone tell me what parts I need to replace the parking brake cable assembly? I can find way too many similar parts to decide what I need to order...

 

You ought to be able to spin one by hand and get it to then coast around on its own for a revolution or two. If it stops in less than half a turn, something is dragging. Have you had your pads replaced? At least on the back, if the pads aren't clipped properly to the pistons they can get skewed and drag (had this happen once when an inexperienced mechanic did a rear brake job for me - the drag was subtle but enough to eventually wear that tire faster than the others). I haven't had any issues with my parking brake, so can't comment on what could be amiss there.