Hello,
sorry I must have missed your post.
1/ the scale setting is global over all patterns. you can permanently apply a scale to a single pattern and store it to flash. this allows for different scales between patterns. please see the manual p.21-22 for how this works
2/ no, there is no way that the current scale change is being visualized
3/ the note length setting allows for really long notes, doesn´t this do what you need?
other than that, I guess it would rather be a setting in a synth, how it handles overlapping notes