Hmm.
1.) I am sure they are very common. As there are also neko's to consider, as they might wear these as well. But yea, there most likely common.
2.) I don't think it's very popular to wear them around though. But maybe it's just wear I live. Xp Umm... Also like hexaod said, people would find it a little weird if a boy would wear something like that. Because it's just so random and also because animal ears would be like the sort of playboy thing I guess?
The common lost a bet thing. I used it at first too when I started wearing my collar to school. But after a few weeks I just said I wanted to. No one knew why or even what a furry was. I didn't really care though, all the stupid comments people made I just brushed off.
On a side note, I wouldn't give a shit =P I'd wear em to school for fun cause that would kick so much ass! ^^ I mean, if I've worn a collar to school the fox ears wouldn't be as random as that to some people I guess.