I see what you did there, dude, you thought you would get two for the price of one, yeah? 😛
Okay I'll bite.
MIDI keyboards (or controllers, as they're sometimes called) can be just as complex as audio interfaces. But I'm not going to lay it down completely for you. Do a quick google search for how does a MIDI keyboard work to find some information about every feature they may have.
I can however give you a couple brands that are revered by 99% of the people in small home studios.
They are M-Audio, Novation and AKAI Professional. Anything from them will be great quality, and will feature Logic Pro X and Mavericks compatibility.
Good luck!