Someone had this question but the post "went away". Assuming it still needs to be addressed - here's my response I had queued up:

(1) which jack should I plug into?

(2) will a FC3A pedal work as a foot switch pedal or to I need a different pedal?

Use a different pedal. The FC3A has half damping and uses a TRS connector (tip ring sleeve). The end connector that you're plugging into Montage has 3 sections. You need a simple on/off momentary switch that uses a TS connector (tip sleeve) that has only two sections. The difference in connector speaks to much of your issue here. Electrically this isn't going to work well.

An inexpensive FC5 is all you need. The end connector has 2 conductors, not 3.

(3) What settings do I need to make to have this globally work?

The [UTILITY] settings are system-wide global settings. Particularly this one can only be changed at the global level. This is what you want - so you're done.