I do not listen Heavy metal music very often, but it is still better than country music. 
I don't know, I think I like country music better, at least some of it.  Heavy metal seems to have originated in the United Kingdom inn the late 1960s
Yes, it has roots in blues rock, psychedelic rock, and acid rock.
Maybe I don't like it because their lyrics and performance styles are sometimes associated with aggression and machismo.
Not always. Led Zeppelin, Black Sabbath and Deep Purple  are my favorite, they have a good lyrics.
Maybe, I don't know them very well, but I've heard of them, of course, as weel as from Iron Maiden and Saxon.
I like Iron Maiden, They have a good songs, like "Fear of the dark".
Yes, I think they achieved their initial success in the early 1980s.