What kind of parts you're expecting from that keyboard ? If it's too minimal, you can even get away with a midi controller and some iPad apps.
That's awesome.
So on my midi controller, I'd run the USB output into the Apple Lightning's input. Then what? You have to have the software you wish to use for say organ tones loaded on the Ipad, right? And how do you run the output into a PA system for playing live? How bad is latency?
Thanks!