DV, my own opinion is that the discussions "above the line" are a pretty mixed bag. They primarily involve English-language music...which is reasonable since this is an English-language site.

My own highly unscientific survey of what is there right now is 19 threads involving American (US) music, 21 involving music from the UK (England and Scotland only, at the moment), 14 from other countries (which includes Canada and Ireland), 26 that are unidentifiable without opening the thread, and 17 that aren't about "national" music, per se. The latter group includes obituaries, inquiries about instruments, and this discussion.   One thing about the Brit threads is that they use this forum more than Americans do for "what is happening where" information.

As for folk vs. popular? The question of "what is folk" comes up regularly, and there has never been any consensus on it. My recommendation would be to read what interests you, get into whatever discussions float your boat, and ignore the rest...and welcome to the 'Cat.