Below, you'll see any text that was highlighted with comments from the reviewer.
I knew kids just like them.
I think you could go with and deepen the reader's interest by letting them make their own inferences. Instead of outright saying that Josh is the character's twin brother, let the librarian briefly confuse them (unless they're not that identical). imagining the scene, let the dialogue do the work, and when the action comes, wack the reader with some amazing detail!
None at the moment, can't wait to read again if you plan a continuation.