1-I'm not sure who you meant by "he". Manson was serious, in that he really saw both the racism and the anger over it, and thought he could use that to ignite a racial war. The Crommunist is serious, in that it is a reflection of what society presents, through the eyes of a mad man.
2-Yes, he spent most of his post writing sabout the subject of his post, as opposed to what you wanted him to write about. That is a curious complaint. He has well over a dozen links in the article supporting his positions. He's written other blog posts on different articles, including how racism affects the criminal justice system.
Most importantly, he does not, to my understanding, take the position that there are racist politicians and non-racist politicians, etc. It's that racism is a cultural phenomenon, one that feeds our cognition and infests everyone (including black people).
3-No, the study did try to determine which whites held racist opinions first. No, the study did not correlate racist opinions to people looking black.
5-Canada seems to have a different sort of gun culture than the US. You don't have to be a black man to see the racism that bubbles in the strongly-pro-gun community.