Loving each update!
Also a heads-up for the effect at the Overture at 4:50 (repeating a few times after that): IIRC, in the original track the effect comes from the very original "Machine Run" preset on the Geerdes Volume 1 preset pack (as per the info on
http://www.thhe.dk/Roland_D-50.htm).
Something like "the other sound channel of the preset has the sound effect in it and the Machine Run rhythm is played in the other one", so the effect can be isolated easily.