I don't know if William Byrd III is AI but I have seen pictures of him and he's dark like some of my Byrd cousins. My Byrd's are Senator Robert Byrd's ( RIP). he and I share an aunt and an uncle but I am not related to the senator.
heritage books is his publisher. you can probably find all his books on amazon. I know some are out of print so you may not find all of them on Heritage Books web
As far as the specific Indian books
For So long as the Sun and moon Endure-Indian records form the NC general assembly Sessions and other sources
Villany Often Goes unpunished- Indian Records form the NC General assembly Sessions 1675-1789
Against The Peace and Dignity of the state-North Carolina laws Regarding slaves, Free Persons of Color and Indians.
North carolina General assembly Session Records; Slaves and Free persons of Color 1709-1789 (my family is in this one signing petitions)
he also has books on specific counties. I have the ones for Iredell, Burke/Lincoln/Rowan and Stokes/Yadkin