As for the Horn, I vaguely remember being somewhat disappointed with how Jordan handled it years ago. There really wasn't a proper Hunt, which I thought was a fun idea that he didn't really explore - except the idea that there were all these Hunters wandering around, looking for something that had already been found.
I haven't watched episode 8 yet, but my guess is that we're going to start seeing a greatly reduced plot - even more so than the first season. They have 13 more books to cover and they really can't be planning for 13 seasons. They can't simply combine two books into one season, especially with 8 episodes, so we're probably going to see huge swathes of the books just written out of the show, perhaps including a lot of the GH. Hopefully that isn't too extreme, as it was one of the better books, but they're obviously doing things a bit differently.