Dutchess, it's fine, just brief. You could think about a little more detail.

Market: Why is your audience 13+? What about your book would not appeal to younger readers? Try to think of specific examples. Also, do you think every teen would enjoy it? Think of the social groups that were in your high school. Which ones wound read your book? Which would not? Just in general. There are always exceptions, but you want to get the most bang for your buck. Let's say you had to choose one or two of the social groups to speak with. You could give a talk about the book at one of their meetings, but you could only do it for two of the groups. Which two would you pick? Which would likely give you the most readers?

On your synopsis, think of it more like a detailed description of the whole plot, like an outline in paragraph form. This isn't your sales pitch to the reader. Is your sales pitch to the publisher.

Cheers,
Michelle