Unfortunately I haven't had much time to work on this project lately - but glad to hear you're interested!
Those coding ideas sound good - I'll trying running some of them when i get the chance.
if you haven't seen it already, check out the APP shield from critter & guitari -
http://www.critterandguitari.com/home/store/arduino-piano.php
the code is a bit hard to follow if you don't speak AVR/C, but it's makes some great sounds