While I can't answer any of Russ's questions because I don't play in a One-Man-Band situation, but I am primarily a guitar player who got into keyboards back in the 80s when MIDI provided a way to create backing tracks at home to play guitar over. I was finally able to create drum and backing tracks to play guitar over without having a band in my home. And yes I think having a good chord knowledge on guitar provided a good base for constructing chords and harmonizing on a keyboard. I never claim to be a keyboard player but I can get around a keyboard well enough to play basic keyboard parts and the occasional organ solo in a live cover band ( http://www.redrhythm.com )