If you can think of successes and challenges with individual students, they'll probably ask you about that. Much of online teaching is one-on-one over the phone as well as over the computer. See what you can find out about their learning management system (LMS), which is the fancy term for what programs and websites they use. Ask about them. I'd also ask them about their policies for attendance and engagement (do they require students to do a certain amount of assignments per week or is just logging in and out enough). It may sound weird, but sometimes having the right questions can be as important as having the right answers.