So far I've just been humming melodies and then using trial and error to transcribe them into piano roll. But, I think if I want to take this stuff further, I gotta buy a midi keyboard and teach myself how to play piano.  Since you're self-taught and are a avid midi user (i think), do you have any advice??   Also, how does one CHORDS?!?! All I know at the moment is that I can create major & minor chords and mish-mash them into a sequence, but I have no idea where to go from here, the world of chords seems so daunting...
if you get a keyboard this will all become apparent. just be careful to get one that knows the difference between how loud you played each note. if not this will unwittingly tamper your spirit unnecessarily