1. Answer: It depends on everyone's taste and these rankings change all the time. According to RankMyPorn, at the moment, the top ranked Ebony Female Pornstars in the world are: Nia Nacci, Mona Azar, Anya Ivy, Diamond Jackson, Kira Noir, Ms London, Victoria Cakes, Brittney White, Honey Gold, Jezabel Vessir, but these will change based on what people vote.
2. Answer: It changes. You can see the latest rankings on RankMyPorn.com and also vote on it for free.