Hi Phil,
I'm a bit late to reply, you may already have this figured out, but I'll post what I know:
Here is a screenshot out of one of the parts diagrams for a recent Evolution/Fastcut model:
Also here is the brake pedal setup on mine which shows how the linkages go together a bit more clearly:
As you can see there, they just added the foot pedal alongside the handbrake lever, acting on the same disc brake. There is a long linkage in parallel with the handbrake linkage, running to the front of the chassis where there's a foot pedal attached. So adding the foot pedal should be quite doable if you can make/get the pedal and linkages.
There are actually several different generations - the slightly older ones like mine (2009) just had the foot pedal controlling the disc brake, and a separate handbrake that latches into some stops welded to the rear sprocket. More recently (maybe 2015?) they got rid of that and just had both the handbrake and foot brake use the same disc brake as I mentioned above.
You can replace the pads with any generic ones that fit, so replacements are not too hard to get hold of. Just make sure the brake disc (part 3 in the diagram) isn't coming loose from the axle - if yours is rusted up like most are, it should be fine, but after I cleaned the rust out of mine I had an issue where the brake disc became slightly loose on the axle, thus rocking back and forth and wearing out the key (part 4 in the diagram) that holds it on the axle. I had to put grub screws through the collar of the disc to fix that.
Also, if you have a model with a lockable differential and it is unlocked, the handbrake/foot brake will only act on one wheel (the right hand side one)!
RLP