Welcome Horizon, great choice of car.
Not sure about your other 2 queries but regarding the stop/start, a few people have said it doesn't work in their cars. It has to reach several criterias before it works, I personally always switch it off when I start the car but if I forget it always works. Hopefully somebody who has had the issue will be able to help regarding sorting it for you.
2017 GLC AMG43 premium plus, night pack, leather, intel lights, 360 camera, side steps. = sadly gone
Now GLE450 Premium plus, Selenite, Black/White Nappa leather, Tech plus pack, Driving assistance pack, Tow pack, Off road pack, 22 inch wheels.