I'm not using any of the custom styles. i'm programing everything from scrach. anyway, the volume change problem had nothing to do with velocity change tab. i think the problem was the volume pedal. now when it is disconnected i don't have this problem anymore.
yes, the manual is hard to figure out and yes, the sd1 is very complicated because it has so many features. that's what made me buy it in the first place (and also the great sound quality of drums and bass).
My biggest problem with it is that it has those freezes, and then i must restart it.
about the effect tab (F2) I think every style records it's own type of reverb (global and drums) but not the amount (1 to 16). I overcome this by programing on user rev 1 a very short reverb for the drums that needs less reverb.