My knowledge of Germany is of no use to you. However, Scott now makes a Classic Catalog which has the stamps of the world pre-1941 (ish) in one book. Most library have this either as a reference or check out copy.
Other than that, I just wanted to say I endorse your stated plan:
I'm probably going to give most of the stamps to my nephew, who is just getting into stamp and coin collecting, and to some other folks in my life who are casual collectors