CARNEGIE HALL RINGS IN THE NEW YEAR with a Saturday night gala including an on-stage buffet. The New Year's Eve celebration, which begins at 8 p.m., will be a benefit for the famous New York concert hall. Singers Marilyn Horne, Barbara Daniels, John Aler, and Samuel Ramey will perform a program of vocal favorites and operatic highlights. AMERICAN PLAYHOUSE, public television's acclaimed weekly drama anthology series, begins its eighth year in February. The new season will include 19 new productions and two repeats. Among the planned offerings are the TV premi`eres of the films ``Stand and Deliver'' and ``The Thin Blue Line.'' Dramatic productions include ``A Raisin in the Sun,'' a three-hour adaptation opening the season on Feb. 1, and ``A Walk in the Woods.'' THE FIRST COMMERCIALLY PRODUCED MOOG SYNTHESIZER has been acquired by the Stearns Collection of Musical Instruments, housed at the University of Michigan School of Music. ``It is to the music world what the Wright brothers' airplane was to aviation,'' said William P. Malm, director of the collection. This first instrument was bought in 1964 by the Alwin Nicolai Dance Theater of New York.