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What's your budget?

Right off the bat I'd say Apogee products, even the Duet if you want good quality.

Focusrite iTrack Solo isn't too bad either, 2 in/2 out but a bit clunkier on the go, not a huge piece of kit compared to regular interfaces though.

If you just want one of those interfaces that are more or less just a plug that you attach to your iPad and your guitar, don't expect too much. You'll also want to do a little bit of research before purchasing as some of them are particularly terrible.
 
Have a look at Garageband for recording, drums and such. I don't use it on my Mac but the iOS version is pretty nifty and should get you where you want, app-wise.