Hello everyone

.
I have a question regarding slave women in Islam. I read
here that Muslim fighters could take female captives and make them their slaves and have intercourse with them.
The first question, is Islam-QA a reliable source on Islam? Do they represent a majority opinion among Muslim scholars?
My second question is whether these female slaves may refuse intercourse with their master. Or do they need a valid reason, like illness, to refuse them?
Thanks.
Oh, let me add that I understand that Islam does not promote slavery. From what I understand slavery is not a sin either, though freeing slaves is seen as a good deed. Is this correct?