3. On a 36” waist with a tartan sett of about 13 cm (5 in) would a pleat reveal of 2 cm (3/4 in) with a depth of 10 cm (4 in) be reasonable to expect for an 8 yd kilt? (24+ pleats?) Would more be better? How many? Deeper pleat? How much?
A tartan sett of 5" is pretty small and unlikely on any tartan above 11 oz weight. Most 16 oz tartans have setts in the neighborhoof of 7-10".

OK, now for the more complicated part. Because tartan kilts are pleated either to the stripe or the sett, the depth of the pleats is governed entirely by the size of the sett. You can't just decide arbitrarily what the pleat depth will be. For example, an 8" sett pleated to the stripe would make a pleat every 8", which would give a pleat depth of about 3.5" if there were a reveal of 1", because (8"-1")/2 = 3.5". If the kilt were pleated to the sett, the pleats would be slightly deeper because it's slightly more than 1 sett between pleats.

The number of pleats is also not arbitrary but, rather, a function of how much cloth you have for pleating (which depends on how much you choose to use for the whole kilt and how big a person you are) _and_ how big the set is. If you have an 8" sett and 200" available for the back of the kilt, you'll get 27 pleats if pleated to the stripe and probably 25 if you pleat to the sett. If the sett is 10", you'll have only 20 pleats if you pleat to the stripe.

So, you just specify an 8-yard kilt and trust the kiltmaker. They'll look at your measurements and decide whether you really need a 9-yard kilt for the tartan you've chosen or whether 8 will do. After the yardage is chosen, and the style of pleating, there is literally no choice in the number of pleats or their depth - it's govered by the tartan you've chosen.
Barb