“So” is a habit, as are rising inflections. The latter seems to be a bit epidemical. Repeating the name is a common technique to remember names. Could be mandated by the station. “Sorry, what was your name again?” could be embarrassing to both sides. Especially in a high turnover situation, like radio, where countless people call in in rapid succession, remembering every name on the spot is nigh on impossible. Hence the repetition.