They don't "collect" anything, in the traditional sense. Every single profile has been re-worked either in a minor or a major way. Not one page is exactly the same as the previous Handbooks.

Yes, the HCs' contents combine the profiles from the 2006-2007 A-Z series and the 2004-2005 themed series (although not every single character from each of these may have been included). They also add new ones. It's basically a completely new Handbook series, building off of the material from 2004-2007.

And bibliographies are online-only.

-Jeph!