> the "book" subject comes up. The way they look 
> and the odd sized pages doesn't suggest a "book" 

Studios do photocopies of the original story 
boards/concept sketches and distribute them.
They are usualy sold by pack, sometime stapled
together. (and naturaly, people make other 
photocopies of them)

A few studio make real books with such drawings 
but that's not common. (I think there is some on 
AMG OVA for example) Also, sometime the character 
designers (or other) makes doujinshi with such 
drawings. (Like the Miyu or Lodoss ones)

Cheers,
Yann Stettler