Let us examine the definition of rock here.
11. b. to use, wear, or display in a showy, self-confident manner or to great effect:
Only you could rock that hat!
Here is a list of things that Prince did (according to the author):
- He rocked a braggadocio guitar.
- He rocked spandex.
- He rocked eyeliner.
- He rocked a feminine ache.
- He rocked a chest full of hair
- He rocked high heels.
- He rocked a proud blackness.
So Prince wore/displayed these these things in a showy manner.
It sounds awkward to me, but Prince "rocked basically magic", could mean that he was (basically) able to wear/display magic. I would take this to imply that he was magical.
So, instead of listing a list as I listed above, the author squeezes it all together in one sentence. I would say that this is a deliberate, rhetorical decision made by the author. The effect is to give you the impact of how great/interesting/quirky Prince was. So I don't believe it is a "misuse" of commas. Instead, I would say it is an advanced way to omit commas.
So, you could break up the sentence and say
He had a feminine ache and a chest full of hair.
But that doesn't have the same feeling as the original sentence.
Number 7 means that he showed pride in being black (African-American). He wore/rocked his blackness with pride. This is figurative speech since one does not wear their skin color.