In the original book, PoC were 'children of Ham' and given the option to be shipped off to their 'homeland' (they were actually then dumped in the ocean).
Bruce Miller made the deliberate choice not to include this in the TV series for a few reasons. 1) time has moved on since 1985 when the book was written 2) he wanted to tell the story of women and have that the main focus 3) if he remained true to the book on this issue there would be no black characters at all as they'd have been sent away during the initial takeover, leaving the show open to being criticised as racist for not having BAME actors. So he made the decision that fertility trumped everything in Gilead.
Re disabled babies, they are 'shredders' and killed at birth in both the book and the TV series. It was briefly referenced iirc. We also had a flashback scene at some point in which people with Down's syndrome were rounded up and taken away somewhere, presumably to be killed.