There is also the return of the Nac Mac Feegle, the little pictsies from Carpe Jugulum. These are a different tribe, but they will be the ones we learn so much about.
And other than short stories, I think this is the first Discworld book that doesn't have Death in it.
Recurring characters and themes that appear in this book:
Jolly Sailor Tobacco
Miss Perspicacia Tick
Pictsies / Wee Free Men
Quirm College for Young Ladies
Roland, son of the Baron
Special Sheep Liniment
The Baron of the chalk
The Goode Childe’s Book of Faerie Tales
The Nac Mac Feegle
The Queen of the Fairies
Wentworth AchingYellow sick toad