Hi
It’s the 8th episode of the second season: “Kill the messenger”.
The scene where he is reading on an eBook reader appears really in the end of the episode, and yes it’s impossible to recognize the model - they keep it perpendicular to the camera and one is never able to see the screen…
Castle (
http://en.wikipedia.org/wiki/Richard_Castle) likes to have poker sessions with his writer buddies, and yes they do appear as themselves, at least James Patterson, Stephen J. Cannell and Michael Connelly do… very funny having they argument with Castle (the actor Nathan Fillion) about the supposed real crimes he is involved in the episodes.
Best regards,