http://www.alesis.com/io-dock-ii
Could this be an option? It would also provide you with a nice, solid, slanted platform to keep your iPad solidly in place while using the on-screen DJ Player features. It does have some midi features, but that is less interesting to you, right?
(Balande?) Jack outputs, additional XLR inputs (not needed in your case I am guessing. And obviously it would charge your iPad while playing.
I am not sure if you can use the built in “phones” for your cueing, but since it seems to dock with the side with the headphone plug facing outwards, you should be able to plug them in there.
Hope that helps.