Book illustration: Dummy!

Yey! Feel like I have come a long way, but I still need to make the actual illustrations.

And there is a lot of problems that needs to be solved. For instance: I want to work with paper, but how
to incorporate the paper with the drawings? And how difficult and far off can the illustrations be?
Another one: should I change the format on Isaura and Bauci, to get a more vertical feeling?
If I do, how can I maintain the cohesive feeling?