I have a Free Model CE with the same type of motor. First like motors of that vintage it has oil holes. Might just be dry.
Second, if it locks to the machine head like mine does, it uses a series of interrupted dogs and can be rotated till the drive wheel is too tight against the hand wheel.
I suspect the face plate will come off by removing the screw at the top and then working it off. You shouldn't have to remove the tension.
As for the rest of the questions I don't know the answers.