Damien's a jerk. Just saying.
Guineas spends pretty much all of his time in half-guinea piggy form, and cannot speak like a human while in that state. He is vastly different from Grace in that regard, as is Hedge. Both Guinease and Hedge wind up with more animalistic heads than Grace does.
As for "Timmy", it's a reference to the old Lassie television show. Lassie was a dog, and Timmy presumably fell down wells a lot. That may not be accurate, but I've seen more parodies tha actual episodes of the show (of which I've seen approximately zero).