Dave,
Disk loading refers to the single disk, as it is that diameter which acts on the air, and determines the induced velocity (the size of the pipe thru the air is pumped).
Mart,
The Black Hawk and S-76 cross beam tail rotor was the inspiration for the Comanche main rotor. The spar twists or bends as needed, without bearings. The torque tube is the way that the twisting for feathering is spread across a more length of spar so that the rotation is less per inch of spar, and thus the deformation stresses are much lower and more allowable.