On the NPS, "Tell us why you gave this score" is enough.
Regular conversations should be a mix of structured stuff (a demo of your latest changes or enhancements - almost certainly followed by feedback. You should aim to get a broad group to attend this. Pay attention to feedback that is off-topic - are you working on solving the right problem? Validate you next moves with the group - will this solve a problem you have? The trap to avoid is having one or two vocal users dominating your roadmap) and less structured stuff (chatting to someone who uses the platform, seeing what comes up, what other opportunities might exist to make a small change to the platform that will remove some pain. You aren't just coming up with feature ideas, or finding out about paper cuts you could prevent - you're also collecting stories about the work you can use to talk to users and stakeholders).