In early April the megabillionaire hosted 150 students from the University of Pennsylvania's Wharton School (which Buffett attended) and offered Fortune the rare opportunity to sit in as he expounded on everything from the Bear Stearns (BSC, Fortune 500) bailout to the prognosis for the economy to whether he'd rather be CEO of GE (GE, Fortune 500) - or a paperboy. What follows are edited excerpts from his question-and-answer session with the students, his lunchtime chat with the Whartonites...