You are committing common low-information error : Judging a geographically alien society by your own contemporary standards. That usual happens when commenting, scholarly or otherwise, about remote historical events, or remote geographic subcultures.
Context is everything.
Presumably, slaves have no income, save material minimum subsistence provided by th 'masters.' It is impossible to answer those questions. The one about education is particularly naïve in the cruelty inherent in the question.
Normally, the answers to those questions (in our sheltered universe) would center around the society at large, but in this instance, the society at large, absent the muslims would be only marginally different. Blacks have always enslaved other blacks as far a history can infer (ignoring the nuts who channel presumed totally disappeared written 'history' ironically centered around Timbuktu.)
I guess I am just a low information type of guy.
That’s what I get for trying to be compassionate.
In fact I was thinking about the people who were turned loose on the United States 250 years ago and who still have no education, Affirmative Action Jobs and just elected a descendent of slave traders to occupy the White House.