Ooops. You are quite correct.   Sorry - having a dumba$$ moment.

Someone may be able to come along and give you the specifics of this but in case not:  appendix C to the advanced manual for the POD Pro describes how the unit responds to MIDI and is a reference to the messages that it expects.  The overall Midi Channel for the Pod is found in the HD Global Settings.

--> http://line6.com/data/6/0a06434dfe5c4f7b801d5336b/application/pdf/POD%20HD%20Pro%20Advanced%20Guide%20v2.0%20-%20English%20(%20Rev%20A%20).pdf

For the FC300, the manual is here http://www.roland.com/support/article/?q=manuals&p=FC-300&id=1810998 .  Looks like if you run it in 'standard' mode then the basic patch/bank change functionality should already be there out of the box.  It looks like you get just two footswitches to turn effects and amps on and off, by default, but you can add extra external switches and you may be able to do something clever with the other modes.  You should be able to hookup the expression

It looks like the expression pedals on the FC send on different CCs than the ones expected by the Pod, by default (FC uses #7 and #1, Pod uses #1 and #2) but you may be able to remap these. 

Brace yourself for a learning curve!