I can’t speak to an expression pedal but I just got this foot switch from Amazon and it works tremendously well to switch between the 4 channel presets.
No that's a momentary switch, you need a latching one.
This should work
You'll also need a trs cable
Hosa FSC-385 Footswitch, Guitar-style, Dual-latching https://www.amazon.com/dp/B000VXKUL0/ref=cm_sw_r_cp_api_i_La.-EbPN5THBE
the switches are both latching. start on patch 1, click once for patch 2, click again for patch 1 same thing for bank. It's this switch
I'm thinking of just using 2 layaround leds and resistors just as an indicator and spending more time playing.