JAMES A. MICHENER: A BIOGRAPHY by John P. Hayes (Bobbs-Merrill: $17.95). What could someone expect from a biography of James A. Michener? A larger-than-life book weighed down with exacting detail; a globe-trotting life story covering decades, generations even, full of colorful, heroic accomplishments? But John P. Hayes' "Michener" is an unassuming book--written with full cooperation by Michener--that follows the legendary author from the poverty of his childhood to the wealth of his later years; from his home in elegant Bucks County, Pa., to his many wanderings abroad. Just how does one man weave gigantic stories about whole states, countries, industries? Hayes does not go far enough into the nature of Michener's work habits, a shortcoming here. Since publishing his first novel in 1947, at age 40, James A. Michener has remained one of the most popular American authors, despite cool critical reception. His fans are legion, keeping him right up there on best-seller lists coast to coast. Hayes's admiration for Michener is evident, which sometimes blinds him to the quirks in the author's character. For example, after several years of close collaboration, Hayes received a form letter from Michener informing him of another biography in the works as well as two other photographic compilations. Nonetheless, this is a well written biography, and fans of Michener will get their first in-depth look at him.