To your point above - all non-fiction by Samuel R. Delany:
Silent Interviews: On Language, Race, Sex, Science Fiction, and Some Comics: Collection of Written Interviews
http://www.amazon.com/Silent-Interviews-Language-Comics%C3%91A-Collection/dp/0819562807
Longer Views: Extended Essays
http://www.amazon.com/Longer-Views-Extended-Samuel-Delany/dp/0819562939
"By radically reworking the essay form, Delany can explore and express the many layers of his thinking about the nature of art, the workings of language, and the injustices and ironies of social, political, and sexual marginalization."