“Every day I write the book,” sang Elvis Costello on his first U.S. Top 40 hit, and this year he is indeed writing one. The iconoclastic British rocker, who’s chased his muse through the most diverse of places, from punk to bluegrass, will let it all out in prose on the hotly anticipated memoir Unfaithful Music & Disappearing Ink. And now, Universal Music Enterprises, the home base for Elvis’ catalogue for nearly a decade (following stints at Rykodisc/Demon in the 1990s and Warner Bros./Rhino in the 1990s and 2000s), will issue a…