Not sure how it looks with polarized sunglasses, but in the past I was unable to see the 12.1" clearly. I have looked at the screen today with matte screen protector on it and I have to say that I am not impressed and it pushes a strong yellow tent. So I would not recommend the Icarez matte screen protector. I will try another product shortly.
As for displaying the outside temperature, I haven't gotten that to work on the screen apps, but have it working when I use Android Auto. I don't see on the home screen, but I am working on it. I need the outside temperature displayed especially when I run trails or bike in remote areas at 6 in the morning. Would be nice to have that convenience before I get on the trail.