Barnabas regarding threaded comments, we don't have any extension implementing that yet. There's an existing (old) discussion about the feature here https://discuss.flarum.org/d/524-reddit-style-threaded-comments It's probably possible to implement it, but I expect it will require a massive amount of work to correctly integrate with Flarum.
I'm sure there are other discussions about this because I remember discussing the technical requirements to make it happen. Maybe a GitHub issue somewhere.
Similar to comment threads there was this discussion as well https://discuss.flarum.org/d/6151-q-a-tree