I enquired of MM about the plug-in kit, and got the impression is not going to be available anymore.

I'm grateful to you for doing this, David, but is there any indication that it's done anything other than fallen on deaf ears in past years?

I think it's safe to assume a dot means "half the note value" with long notes such as half notes at normal tempo. What else would it mean? But in general, lines and dots vary in meaning from composer...

Enter the notes, then add the symbols indicating a roll. The first example uses a Smart Shape, the second an articulation.

Alt-Shift, not Ctrl-Shift, no? Or have I forgotten customizing it?...