Technical information and LONGEVITY

[Brucaliffo]

Hello,
I have some question about blu-ray that I haven't found on the web:

-Is blu-ray movie affecter by light or UV?
I've read that BD-R have inorganic layer, what about BD-ROM?

-What's the longevity of blu-ray? Panasonic site states 50 years but this is for recordable disc, not commercial movie discs.

-Is important to store blu-ray in vertical position? Are there problems if I store them horizontally?

-I've read that scratches makes them unreadable, because the reading layer is near the surface (0.1 mm) but I have two scratched blu-rays and they play fine.
Is because I didn't see all the film and there could be some artifacts somewhere?

-4K blu-rays have the same technical material and longevity or are different?

Thank you.