Unfortunately, all of the official information is found either in the Tome of Magic or in a Cityscape Web Enhancement on the Wizards website. As far as Errata, the only two changes that I'm aware of is a small error on the mystery use per level chart and that the duration of shadow time gets lowered (boo!). You can find this errata on the wizards website as well.
If you want a compilation of all homebrewed info, look at the tome of shadow that I posted on the wizards boards (where I am a bit better at coding, and thanks again for your offer to help). There are several links to other homebrew areas.
If you do enough searching, of course, you will eventually find the unofficially unoficial changes made by the class' creator, mouseferatu (AKA, Ari Marmell), on these boards, no less.
