I don't know whether Rowling was planning the whole thing out from the start. From what I understand the first book was written basically on napkins from fast-food chains, I don't think she was really expecting Harry Potter to be the success that it was. I do know what foreshadowing is, and Rowling makes absolutely excellent use of it throughout the first few books, probably the best of any author I know (along with caricature, take that Dickens!)

The Ranger's Apprentice series came out a while ago, right? Something like 6-7 years ago? If so, I remember wanting to read that at some point, because the cover was cool. XD