FATHER, DEAR FATHER (247 pp.)Ludwig BemelmansViking ($3.50).
"I was born in a hotel and brought up in three countries,'' Humorist Ludwig Bemelmans tells his daughter Barbara when she asks why all the characters in his books are crazy. "And then I lived in other hotels . . . and the only people you met were odd ones . . . Upstairs was a collection of Russian grand dukes and French countesses, English lords and American millionaires. Backstairs there were French cooks, Rumanian hairdressers, Chinese manicurists, Italian bootblacks, Swiss managers, English valets . . . When I was sent to America to learn...