Propaganda
Superstar
depends on the genre tbh, i guess for more rap stuff a beat maker might master a beat for themselfs not thinking a rapper will lay something down, it happens
nah, it doesn't depend on the genre, man.
you gotta think of the vocals as one of the instruments...in fact, the MAIN instrument, especially if we're talking about rap/hip-hop. you wouldn't mix and master a song then add a bassline afterwards. so if you have a choice, you certainly shouldn't do it with the vocals.
make a solid mix of your beat for dudes to rap over, when you have the vocals, do your full-on mixdown. then you master. once. mastering it twice doesn't even make sense.
a lot of shyt is mastered "for radio", as in, they send out a mastered track which has been tailored for radio and is a bit different than say, how the album track was mastered. it could be a clean version, a radio edit, a shorter version, one with less compression and limiting (sometimes none at all cuz most radio stations squash the audio so hard), could be for some other reason...but they don't master the song, then master the already mastered song again for radio.