Can he finally be himself? Nine months after wrapping up The Colbert Report, the comedian is nearly set for his new role as David Letterman’s heir. Each of his 200 or so yearly shows will be twice as long as his Comedy Central gig — and no more ball jokes, the 51-year-old laments. He’s involved in every step of preproduction, from HVAC to editing. But asked to explain what it all means, the devout Catholic talks about serving God, “that we might be happy” — in this world and the next.