The material is similar to that of the Jass cards. The surface is sealed. The backing is paper or thin cardboard.

No, a 2+ can only be countered with a 2+ or a 4+ with a 4+. This is often confused - you might have to take up to 8 cards or so, which is not true. Have fun!

I don't know, I gave away the UNO cards. LG