The earlier portion should be in the form of a conversation, not some point and shoot questions. I think you need this to get at the details you as an interview

The earlier portion should be in the form of a conversation, not some point and shoot questions. I think you need this to get at the details you as an interviewer need, but it doesn't mean they can't interject questions, that's how conversations work. 10-15 minutes of candidate led questions, gives them the floor entirely after that, and I've never found it to not be enough time.