I second the comments about Hurst's, The Art of Urban Cycling, as well as John Allen's Street Smarts. Hurst is fun to read and Street Smarts is concise. John Forester's Effective Cycling is good if you can get by Forester's obnoxious personality. He also has a video that you might be able to get from your library. It's dated (1970's, I think), but according to Bicycling Magazine, at least one school that trains bike cops still uses it as an intro.

With the exception of Street Smarts (which is free), I'd suggest checking books out from the library. There's no need to fork over the cash until you know you like the book.