My current recommendation for mounting footbraces is:

Drill the holes for mounting the footbraces oversized. The holes should be about twice the diameter of the mounting screws. Tape the underside of the holes so that they will hold epoxy. Fill the hole completely with epoxy. Let it cure.

Now drill the holes to the proper size and mount the footbraces with screws through the holes.

The reason for doing this is to distribute the force of the hardware (keeping the skin from being crushed while tightening the screw and making the area pushing against the hull larger) and sealing the grain of the wood.

You do not need to glue in the screws. This does little to strengthen the mounting while making it more difficult to assemble. If for some reason you want to glue in the screws, wax them first. This will let you remove them later.

My recommendations are constantly changing as I experiment with new ideas and customers recommend different and better methods.