THE RISE to fame of Mickey Mouse is a case of rags-to-riches, rodent-style. "Walt Disney had been working to exhaustion on my first film, Plane Crazy, reminisces Mickey. "In those days I was poor as a church mouse. Didn't even own a pair of shoes. When the picture was finally previewed, I looked for the nearest hole. The pint-sized performer figured it would be a flop-but the public thought otherwise. There followed the celebrated "Steamboat Willie," and, later, "The Lonesome Ghost, in which Mickey first teamed with Donald Duck and Goofy. A high point came when Mickey joined Leopold Stokowski and the Philadelphia Symphony Orchestra to do "The Sorcerer's Apprentice" in "Fantasia." […]