Answer to Question 1
Three-lined (AAB) stanzas:
The first line is repeated in stanzas one and two, the third line always rounds out the thought of the first line(s) usually with an ironic, witty punch line, such as,
. . . if one woman don't like it, there'll be a hundred and five that will.
Stanza 3, with a different second line, follows an A B C text-line pattern.
Blue notesfor example, on the words rollin' tell, want, please and roll in stanza 1
Polyrhythm between the singer and his guitar accompaniment
Typical twelve-bar blues chord progression
Syncopationfor example at how you want . . . tell . . . mama . . . done roll . . . dusk to dawn in stanza 1.
Answer to Question 2
Whites now dominate the audiences for current blues music.