Longtime White House chief usher dishes on pingpong with Carter, the benefits of Trump’s ballroom — and the time he handed Nancy Reagan a bill

He knows virtually everything astir the presidents — from the toothpaste they usage to the mattress they slumber connected — and present Gary Walters, the White House’s longest-serving main usher, is opening up astir his decades-long career. ITK caught up with Walters, who worked astatine 1600 Pennsylvania Ave. from 1970 to 2007, up of the…