Typically, what I've seen is that with custom & semi custom cabinetry, the vanity table is a seperate piece with no base or legs. Because it's attached to the sides of neighboring cabinet pieces, you can make it any height you want. 35 1/2 must be the kitchen height cabinets because Kraftmaid's bathroom cabinets are 33in and other "bathroom height" cabinets we looked at were on average 31-32 inches but kitchen height was also offered. It varies and depends on the company. In otherwords, you can figure out what a comfortable height is for you and install it accordingly. The differences in heights will add some nice interest to the space.

The 10-12" sounds right, our table is 36" high with 24" stools. Think our 31" island is just an awkward height, like halfway between a stool and dining chair height. During construction, I pulled one of those plastic outdoor chairs on site to it and and counter felt uncomfortably high, too far up my chest. Could be tight with 7" space for a 24" stool but think its our only option. Hoping a padded stool may drop an inch or so when sat on for a bit more space.

Including the seat. I think ADA compliant is a little taller than what a manufacturer chooses to call "comfort height." I was so confused by that term when we bought those toilets! Didn't really care though because we chose Caroma based on using them a lot in Australia and were sold on the dual flush thing. It turned out to be a really good height when I had a knee surgery a couple of years after that!

What is the height from floor to seat of the Leather Counter Stool With Back sold by ShopLadder?