As the lead singer of The Gap Band, Charlie Wilson had huge hits — as well as a debilitating drug habit. He tells his story of recovery and rebounding to the top of the charts with the help of Snoop Dogg, Justin Timberlake, and Kanye West in the new memoir “I Am Charlie Wilson.” Also, The Silver Lake Chorus commissions new songs from indie rock’s greatest songwriters, and we hear the story behind one Aimee Mann wrote for them. And, for a poet obsessed with the passage of time and the end of the world, Mary Jo Bang has a surprisingly upbeat personality.