Correct, in the 7 seat configuration 7 seats have heat and the first 5 have cooling. In the 6 seat configuration 6 seats are heated, but only the front 2 are also cooled.
Heated front seats are standard. The sub-zero package gets you second (and third, if equipped) row heated seats along with a few other things.With the production configurator it looks like you need the premium package to get ventilated seats. But, do you have to get the sub-zero package in order to get heated seats in the front row?
Are these ventilated seats just the seat bottom, or does it include the entire seatback as well? One of my biggest complaints about most "cooled" seats is that all the cooling is focused on the butt and thighs, so your back (especially upper back) continues to sweat even at the highest fan setting.
Clear as mud! ;-)
If someone would click on the "learn more" text in the design studio, you could find out if it is only the bottom or also the back. See this video Tesla Model X Production Design Studio Walkthrough - YouTube (8:00 for options and red "learn more" text)
Unfortunately i am not a reservation holder or otherwise capable person to get acces to the design studio of the X.