OhSoInsane:
For the first scenerio you described, I got something from the Musicom's manual:
"The EFX Mk III contains a XPDL port for expression pedal input or external foot switch input. This can be used to alter parameters(via MIDI) in effects device that offer this capability. The MIDI Control Change Value is transmitted corresponding to the position of expression pedal or external foot switch"
However, it may be that it can only transit CCs on 1 channel at a time. My reasoning for this is because if you go to Page 12 and look at the diagram, you only see 1 CCs column. Please have a look:
http://www.rockbox.com/EFX_MkIII_Manual_v1.0.pdf
Another option here that some people use is to have all the pedals on the same MIDI channel or set to OMNI (listen on all MIDI Channels) this way you could send the MIDI CC for the expression pedal from the controller and it would control what ever is listening for that MIDI CC on that MIDI channel.
you would have to get a bit creative with the MIDI programming to avoid clashes and the Factors make this a lot easier as they have the MIDI Map function where you can tell them what preset you want when they receive a particular PC number, by default it is PC#>Preset# eg 1>1:1 2>1:2 3>2:1 4>2.2 etc but with the MIDI maps you can set it to 1>15:1 2>1:1 3>27:1 etc.
I know some people run them this way and it works for them, personally I like to keep things on separate channels and keep everything as "default" as I can to keep it simple
