The average swede likes to pretend that they are not patriotic, when in reality they are, it's one of our more laughable national traits.
I never see anything like that though hehe, I think pretty much everyone is fine with people having the swedish flag and jersey out when it's a sports event though. I nicked a huge swedish flag from a corporate parking spot some years ago while walking home in a drunken haze, I mean huge, it covers 5-6 seats in the arena!
Never gotten a comment about it being weird tbh.
There is loads of black music, you may choose to call it something different, but it's quite a commong expression since a lot of the people who started out doing it was black afro-americans. Jazz is one such music genre.