A Deluge [1] or a NORNS+GRID [2] rig is also a good way to get the shape-based chord understanding without an investment in clavier-thought:

[1] - http://synthstrom.com/

[2] - http://monome.org/

Actually, just the NORNS itself is going to get you booted up with some ridiculously fantastic music theory, especially if you're the kind that reads the source ..

Not sure on how much use it is without Ableton, sorry - I'll need someone else to answer that

It requires Ableton (there might be unofficial integrations with other DAWs). I have an Akai Force which is completely standalone, not even a computer needed. But I'd honestly recommend Ableton+Push unless someone really needs it to be standalone.

It's a MIDI controller, so in order for it to be useful it has to be connected to something that can accept MIDI inputs.