Adam,
Sounds to me like you have a pretty good basic understanding of some helicopter theory regardless of Ascend Charlie's comments. If AC doesn't have the time he should skip past the question.
Here is my take-
The term "Rigid Rotor" is very confusing. "Hingeless rotor" is a better description because the so-called rigid rotor is not really rigid. The "rigid rotor" is actually designed to allow flex near the hub. So the word "rigid" should not be used anymore but it still persists.
Confused?
The books are sometimes hard to understand and often wrong, all you can do is keep trying.