some short answers to some of your questions below:
1) Starting with a blank track (all steps are off), by default the incoming notes are recorded on the position where you play them, within a resolution of 1/192. This basically defines the STA value for the just activated step.
The next time a note falls on this active step (or rather within the 12/192 time interval of this step), the pitch will be "stacked", effectively forming a chord, the beat offset will be discarded.
2) A step represents a note, not a period in time. LEN will therefore determine the time it takes for a note off to be sent for that note, but will not influence the time it takes until the next note on.
3) Our users are more suited to answer that question.
4) The OS is open source. See the link provided in the service area of the web site. Or check out http://sourceforge.net/projects/genoqs/