“People who you’ve read about or know about – there they are looking right at you.” Art curator Kara Vander Weg is talking with me about global art gallery Gagosian’s major new Richard Avedon retrospective, in which 150 individuals – ranging from the younger Barbara Bush to Khloé Kardashian to Spike Lee to Elton John to Renata Adler to Vander Weg herself – each selected a single Avedon photo to celebrate. She’s explaining the…