Actually CC is quite a good engine in my opinion. Indeed a few bugs, but once you know them you can avoid them pretty easily.
Also there are a bunch of pretty good plugin for CC. And I think at the moment C2 hasn't caught up with all of CC's feature yet.
In short, I don't think you wasted your money.
Well, I don't know much about the quality of the ebook. There's no official ebook for cc as far as I know.
And yes, CC and C2 are very similar, so learning CC isn't a waste of time 'cause C2 works the same way.
So enjoy (: