OK... On to my second program change question...
Can I store two MIDI presets against one song so I can switch between two sounds within one song?
If I add two MIDI presets, the last one is the one that become active.
e.g. I want to change between Power Synth and Horns between verse and chorus.
Is this possible?
Yes, you can attach multiple MIDI presets and trigger them at different points in a song. See steps 10-14 and step 16 on this page:
http://www.bandhelper.com/tutorials/sending_MIDI.html