Program change is described here at the top of this page :
http://ixox.fr/preenfm2/preenfm/midi/ Program change
Bank select (CC#0) and Bank Select LSB (#32)
Bank select=0 => BankLSB=Preenfm bank number
Bank select=1 => BankLSB=Combo number
Bank select=2 => BankLSB=DX7 bank 0->127
Bank select=3 => BankLSB=DX7 bank 128->255
By default program change load from the pfm presets.
If you change CC#0 and #32 it can load from combo or DX7 bank.
I think global midi can be different depending on the 6 instrument midi channels.
As instrument midi channels are part of the mixer, global midi is also part of the mixer.
I admit i hesitated before putting it here, but that was my conclusion.
Thanks a lot for your 3 other entries, will have a look later this week.