My country doesn't really have them, only old houses do. It seems like it would be a lot of work to make them and most houses are just build on concrete slabs now anyway.
I live in an apartment, so there is no basement. I would just... die, basically. There's a pretty steep decline nearby that I could maybe hide at, but considering a lot of the danger in a tornado is flying debris, going outside to hide in the woods may not be the best idea.
I have no idea, tornadoes are so rare here I can't tell how much damage one would do. There should be a room secure enough in my house though.
Depends on tornado strength, but they're generally pretty safe. The best option is a safe room that's made out of steel and also has large bolts anchoring it into the ground, but it's pretty rare for anyone to have those. I've seen commercials for them, though.