QuickTime (MP4) | iOS MP4
You may have already seen the press release for the Focusrite iTrack Dock - its able to take the iPad mini or full size with a cunning sliding lightning connector. It gives you a pair of decent mic preamps and line out, kind of like the Scarlett 2i2 but for iPad.
I wont re-print all the details, you can see that here if you want.
On the fly arrangement of chords and melody