I do. But I live at a fairly high altitude. If I don't put on the sunny, I'll get a bad burn in ~15 minutes of being outside. That's short enough that mowing the lawn or taking a walk will burn me. I got tired of always having a bright red nose or arms that just hurt. So, now I just have a bottle sitting by the door and schmear some on before going out. Also stopped wearing sunglasses, as they make burns worse. Again, I live at altitude.

I do. Aside from sunburns, sunscreen helps to prevent or delay photoaging and reduce inflammatory response to UV in the skin - meaning less acne, rosacea and hyperpigmentation. I use only European sunscreens with proper UVA protection.

Yes the recommendation is SPF15 every day, even in winter.

Many daily moisturisers will have at least SPF15 so it's no hardship since you're already moisturising every day anyway.