The book seems to be a pretty good summary of the differences between the narratives in Matthew and Luke. It's well organized, with good graphics. I like the way you've described the differences in the stories, without having a hostile tone; that's a hard balance to hit.
Some questions and nits:
1) Is the intended audience young readers or adults? The first pages have the feel of a children's story, with simple sentences, but by the last pages you're using a larger vocabulary than most elementary-school children would have. It can still work as a book for adults, with the children's-story part being a simple telling of the stories, but I wasn't sure how to read it.
2) If you're mentioning Q, you should probably also mention Mark. Many of Jesus' sayings come from Q, but many of the stories come from Mark.
3) In the Bible passages you quote, make sure to acknowledge the translation you're using. Most modern translations are copyrighted. If you're going to sell your book, you probably need to get permission from the publisher of the translation. You've seen those notices in books: "Scripture passages are taken from the New Revised Standard Version. Used by permission."
4) I more often see John's father's name as "Zechariah", but you're right to be consistent with the Bible translation you're quoting. What translation is it?
5) I'm currently reading Jesus Through Middle Eastern Eyes. In that book, the author claims that for most first-century peasants in Palestine, the building where you kept your animals and the building where you kept your family were often the same building. If that's correct, there's not much conflict between saying Jesus was laid in a manger and that Jesus was in a house. I'm not enough of an anthropologist to research this claim for myself, but it's something you might take into account.
6) If it were me, I think I'd make Mary and Joseph a little more olive-skinned, given where they lived, but go with your own artistic vision.
Aside from those nits, I think your summary of the two stories and the issues surrounding them is good.