This website is all about Xessus.
Spoiler alert: in the books, you find out about the world at about the same speed as the characters. On this website you might find something out that you aren't supposed to know until later. But I'm guessing that if you are looking at the website, you will be okay with that.
You can order the books from Amazon at http://tinyurl.com/j2ewyap, which also lets you "search inside" - so you can read quite a bit of it to see if you like it, and you can see some of the illustrations.
School visits - for details see here.