Page Six alumna Paula Froelich is showing up all over: with and without her clothes. On Thursday, a fully clad Froelich will read from her best-selling novel, “Mercury in Retrograde,” now in paperback, at Borders on East 57th. On July 7, her ex-boyfriend, Les Rogers, is part of a group show at the Haunch of Venison gallery at Christie’s in Rockefeller Center. Look for Froelich, who posed naked with her mini-dachsund, Karl, for a series of Rogers’ oil paintings.