The social awkwardness and inappropriate behaviour sounds more like Aspergers to me (on the Autism Spectrum) but of course it is not our place to give a definitive diagnosis.

I see two options (his racist behavior is a no-go, game changer for me). Either you intervene or walk away. Have a very frank heart to heart. Advise him you will not tolerate such antics else you will end the friendship - and stick to this threat.