One-third of the full-time residents of Greenport are Latino, the first of many facts to surprise me in this lively and valuable contribution to understanding the Village of Greenport today. In her book “Village of Immigrants: Latinos in an Emerging America,” Diana R. Gordon, a retired academic, has drawn a portrait of the village that is thorough but not pedantic, granular at times, sweeping at others, and, at its core, a personal story: Ms. Gordon lives in Greenport, it is her hometown, and she wants its Latinos to stay and prosper.