I can only bring my anecdotal evidence or illustration to your point 3. About 15-17 years ago, my nephew was sent to take an IQ test as one of the parameters for admission to a Gifted class at his elementary school. For all but blacks, the threshold for admission was 136. For blacks, it was 118. Such a DEI in my Blue county:) That is, although it is not publicized anywhere and formally since the late 1980s it is not politically correct to talk about it anywhere, school administrators and practical school psychologists are well aware of this IQ gap and quietly lower the barriers for blacks.