Re sunscreen, I honestly just don't know. I think it probably requires a deeper conversation. I'm in Los Angeles and the sun is pretty intense year round, and we've been told over and over again that skin cancer is practically inevitable if you don't wear sunscreen. But, if you DO wear sunscreen then you miss out on the Vitamin D.
Aside from the skin cancer scare stuff, there's the other drumbeat that sun = wrinkles so that's another reason to wear sunscreen. But then, wrinkles are cool, ya know?
I've sorta split the baby on this and wear sunscreen on my face, but not on my arms or anywhere else if I go to the beach. But who knows? Maybe someday we'll find out that the sunscreen industry has the same lobbyists/talented ad folks that the rest of the beauty industry does?