I got an email with an interview request about a month after the application window closed. Less than a week later, I had a single very friendly Skype interview of around half an hour - was interviewing simultaneously for the fellowship or apprenticeship spots, with the possibility of a remote contributorship. Questions were pretty simple - about writing background and experience, plus a couple to demonstrate enthusiasm for the Onion's work. I got the sense that the whole thing rides 98% on the portfolio and the interview is essentially there to make sure you're not visibly a murderer.