You can do it several ways with the use of your Behringer desk.
1)Hook up the microphone into the mic-in on the VL2.
2)Plug your guitar in the guitar in on the VL2 and/or run MIDI-out from your keyboard to MIDI-in on the VL2 and/or connect an aux out from your Behringer desk and hook it up to the AUX-in. (The aux out on the Behringer is used to send music to the VL2 in order to determin the harmonies)
3)Connect the main-out from the VL2 to a stereo-input on your Behringer desk.
4)Make sure that you DON'T send any signal from the stereochannel connected to the VL2 on the Behry to the aux-out you used to feed aux in on the VL2! (you'll create a feedback loop if you do)
1)Plug your microphone into the Behry desk.
2)Connect aux-out 1 on the Behry to the line-in on the VL2.
3)On the Behry desk make sure you send only the signal from your microphone-channel to aux 1.
3)Plug whatever instruments you use into the Behry desk
4)Connect aux-out 2 on the Behry to the aux-in on the VL2
5)Send any music channel you want to use to determin harmonies tothe VL2, using aux 2 on the Behry.
6) Connect main out on the VL2 to a stereo input on the Behry.
7)Make sure that you DON'T send any signal from the stereochannel connected to the VL2 on the Behry to either aux 1 or aux 2! (you'll create a feedback loop if you do)
I don't have the footswitch, so I can't help you with that one.