Frank Rizzo's career as an outspoken radio talk show host is off to a good start. The former strong-arm Philadelphia mayor made his debut on station WCAU in Philadelphia Wednesday, and the result was a barrage of phone calls. The first hour of the afternoon show drew more callers - most of them Rizzo fans - than any hour in the station's history, and the next 30 minutes even topped the first hour. Rizzo, a Democrat who converted to the Republican Party, spent a lot of time discussing the presidential election - praising George Bush, saying voters are fed up with the Democratic Party and blasting media coverage of the campaign.