first response to the concept of "Whiteness"

In the introduction to The Great White North? (Carr and Lund), George J. Sefa Dei writes that

"Racism is about maintaining White dominance and supremacy" (viii).

And later:
"As alluded to, Whiteness cannot itself be essentialized, especially when embodied Whiteness intersects along gender, class, and sexual lines....Notwithstanding these complications, however, it is also equally important to reiterate that there is a systemization and structuralization of dominance within social institutions that perpetuate White privilege and other forms of oppressions "inter-generationally" and/or through time and space, irrespective of class, gender, religious, language and sexual differences, particularly among dominant groups" (x).

Two questions arose for me out of the reading of this introduction. First, I would like to ask whether racism, fundamentally, is not the stigmatization and differentiation, or polarization of a number of people, based on their race. Racism and supremacy seem to go hand in hand; they both segregate or categorize people based on race, and then apply certain values to that race as a whole. Is racism the act of making race an issue? If so, Dei is he is singling out a particular race and identifying that race with a certain quality. If this fundamental definition of racism does not hold, or racism is not about the polarization of people based on race, then Dei must rethink his terms: he cannot define racism based on an idea of "white," because his definition rests on and expands out of a polarization of a particular group based on race. In making claims about what Whiteness does to people who are white, is Dei himself engaging in a form of racism, a racism that is not about "maintaining White dominance and supremacy"?
So is Dei's form of racism, (i.e. his naming of the category "Whiteness" and then applying it to every White person as being something that every White person participates in "deliberately," whether they want to or not) a good sort of racism, something that he thinks everybody needs to do more of?
Is racism ever good?

Secondly, I am trying to understand the notion of "embodied" vs. "essential" Whiteness.