Cooled seats are just ventilated covers and what basically amounts to a ball-bearing PC fan. A lot of cars have vents under the seat for rear passengers, though (ducts go under carpet), so I'm sure that helps to some extent to pipe cool air up your butt. Having seen how simple they are with the covers off, it does surprise me how effective they can be.
As for dual evaporators, I've never known anything to have them except big SUV's, where the second evaporator is used for the rear AC. 'Dual zone' climate control is just a pair of blend doors in the dash.
And I stand corrected on the R134a flammability. I found the actual technical data for Dupont R134a, and it does indeed list an autoignition point that coincides with the other claims of ~750*C that I see. I'm kind of baffled by how technical info (textbooks, manufacturer training, ect) typically calls it non-flammable. Hell, I believe it even says nonflammable on Wikipedia (yeah, I know, it's Wikipedia...but basic, available info like that tends not to be wrong).
Again, though, autoignition does not tell you everything. That's the temp needed for spontaneous ignition, and it only becomes
possible...it's not a guaranteed bang. I will not pretend to completely grasp these concepts. Going back to Dupont, they even seem to contradict themselves:
http://www2.dupont.com/hfo1234yf/en_US/test_results/flammability.html
...but I can find no specs for HFO-1234yf to compare with the listed data for R134a. They even mention the Daimler study there, and basically say it's invalid because it's not 'real world.' I kinda disagree. They sprayed 1234yf at a hot turbocharger, I believe. It went bang. They did the same with R134a, and it did not. Goes back to the 'unlikely does not mean impossible' concerns of propane. Of course you could have a massive refrigerant release near a hot turbo...why would you claim that you couldn't? Just because all cars do not have turbos, does not exactly negate their existence.