They've compressed the timeline, Shea is now Wil's father not his grandfather and the events of the first book is a mere 30 years ago.
Yeah, I too noticed that off the bat, but did I miss it, or have they not actually mentioned Shea by name?
No, I don't think they have. And if I remember correctly Eventine was about 80 years old in the book, seveal hundreds of years younger than Allanon.