The plain truth is that Mr Pratchett speaks the truth - we all perpetrate folk music to some degree! he has met quite a few "folkies" (I hate the term, btw) - some of whom are considerably worse perpetrators than others... he was at a wedding where quite a few of these were gathered. But he doesn't single folk music out for attention more than any other subject!

I'm not sure which is my favourite book - I tend to prefer the later ones though.

As for characters - Nanny Ogg, DEATH, Susan, Granny Weatherwax...