Re: Waggy Tail
In my experience, a rapidly swishing tail means "agitation" of some sort - not necessarily anger, it could even be excitement. For example, Desdemona will often sit on the windowsill watching all those tweety little birds out the window, and her tail will be swishing like crazy as she contemplates the tasty meal options. But her tail will also swish if Othello is getting on her last nerve, right before the hissing and swatting starts.
Are you petting Bebo while this is going on, or is he just sitting there without you touching him much? If you are petting him, it's possible that the tail-wagging could be saying, "I've had just-about-enough handling, any more will be too much." But if he's staying on your lap of his own free will, it's probably a happy-excited. Just make sure you're not pushing past his had-enough-handling tolerance; you could try backing off the petting (hard, I know!) and see if the purring and tail-wagging continue.