It’s a frigid Sunday afternoon in April, and Andy Cohen is perched on a park bench, ruminating about the ups and downs — but mostly the ups — of his nearly 3-decade-long career in broadcasting. Occasionally, a passerby walks past and smiles, or shyly waves hello. This, it quickly becomes apparent, is a common occurrence for Cohen, 57, who seems to be something of the unofficial mayor of this cobblestoned, townhouse-lined neighborhood in downtown Manhattan, where he — and now his two children, Benjamin, 5, and Lucy, 2 — has been living for 27 years. Everybody, it seems, loves Andy Cohen. Well, not everyone, but we’ll get to that in a moment. He started his career in New York in his early 20s, a precocious, fiercely ambitious network executive with…