Dan Mason will succeed Joel Hollander as president of CBS Radio. A Poolesville native, Mason will oversee the day-to-day operation of the company’s 144 radio stations, including a dozen in the DC-Baltimore area. He will report to CBS head Les Moonves. Hollander has been rumored to be working on an exit plan after skirmishes with Moonves. During the late 1990s, Mason served as president of the then CBS Radio Group. Rather than operating from Manhattan, he worked from offices in Potomac. After giving up his previous title at CBS, Mason continued working for the company as an adviser and consultant. In the late 1970s, Mason was program director at “top 40″ WPGC-FM/AM…..