Dale, you got it right the first time, the Nylatron (and other non-rubber) bushing does not rotate against the trailing arm surfaces, it rotates on the inner sleeve, held in place by the through bolt. The original hard rubber bushes are molded to the inner sleeve and are not designed to rotate on the through bolt. Instead, they act as a torsion fitting, the rubber flexes radially as the arm swings. When installing, the trailing arm needs to be in the mid position of it's travel movement. The best way to find the mid position is to wait until the rear wheels are on the ground then torque down the through bolts. Many a rear rubber bush has failed due to improper installation where the upward or downward swing is beyond the bushings ability to flex.
As far as installing a grease fitting to extend the life of a Nylatron bushing, I have no experience to support the installation one way or another. If one were to do this, insure the fitting is located were the two Nylatron bushings meet inside the arm, also insure there is sufficient space between them to allow grease to access the inner sleeve.