Health plans appear to be having some trouble fulfilling a federal mandate that 80 percent of questions from Medicare beneficiaries about pharmacy coverage be answered within 30 seconds. The fast-approaching deadline for enrolling in a Medicare drug plan may be partly to blame. "The large amount of interest in our prescription drug plans, as the May 15 deadline approaches, means that the wait times are longer than we would like," says Humana spokesman Thomas Noland. . . . New standards that rate insurers on measurement of physician and hospital quality and the degree to which the insurers act on the results received the backing of more than two dozen of the nation's largest employers. The National Committee for Quality Assurance will begin surveying plans on July 1.