1) Abs are ‘braced’ and not ‘drawn in.’
2) Feet: toes are slightly curled up to shift balance back toward heal (to prepare for squats, deadlifts, overhead presses) and to shift center of gravity back from the anterior dominant position and over the ankle, knee, hips, spine, ear, etc. However, they maybe simply also use a flat or a foot ‘grab’ on the floor like a suction cup if this is more appropriate for them.
3) Remember, this is ‘athletic neutral’ for strength training purposes. Not exactly textbook anatomical neutral. This is the safest position to hold each structure to move and receive loads. Cuing ribs down is appropriate for overhead pressing movements only. Cuing ribs down, squeeze the glutes, and abs in are not good or safe cues for squatting, deadlifitng, or Olympic weightlifting unless it is a body weight or pvc pipe load. Those particular cues will promote hollowing out or flexing of the spine which is the last thing you wan’t when you are loading the spine. Better cues for these cases are reinforcement of the posture hold positions or simple things like, ‘stay tight’ (movements not muscles).