The Question and Answer section for Wide Sargasso Sea is a great resource to ask questions, find answers, and discuss the novel.
"White cockroach" is a racial slur. Antoinette foolishly slaps Amelie her servant, when Amelie makes what she perceives to be an inappropriate comment. White cockroach is the name given to the Creoles.
The three paragraphs that open the third section are italicized and written from Grace Poole's point of view.
The two main groups of people living in Jamaica are the rich, white property owners, and the poor, freed (formerly slaves) blacks.