Hi guys,
I just did it myself. The only element of difficulty is drilling on the spot you marked without the drill bit slipping. You can use a hammer and corner of a chisel (or similar pointed sharp tool) to make an indentation where you want to drill. This will be sort of a pilot hole/point so the bit doesn't slip or move when you drill. Obviously start with a small drill bit and then size up to fit the screw.
As for the footrest, it came as part of the pedal package. It is only fitted to the existing plastic foot rest with double sided adhesive. It just happens that the part with the metal plate covers the existing foot rest. It looked like it would fit if I cut out all the black plastic, so I whipped out the jigsaw and did a bit of cutting. Then I just cleaned up the cut edges with a fine metal file and some sand paper. I taped up the front with masking tape so it wouldn't get scratched when I was cutting.
