Carreras on the Move: Tenor Jose Carreras will play the Greek Theater May 16 as part of a spring tour of the United States. His tour begins May 12 at Carnegie Hall and includes a May 29 appearance in San Francisco. Carreras, who is serving as artistic and music director for Olympic festivities in his hometown of Barcelona, says those events will include a "Greatest Hits" operatic extravaganza featuring Teresa Berganza, Montserrat Caballe, Juan Pons, Jaime Aragall, Placido Domingo and himself. . . . Carreras' stop at the Greek, incidentally, is part of a classical music subscription series that also will offer pianist Misha Dichter July 20 and sister pianists Katia and Marielle Labeque Oct. 28.