I'd place the latter two on the same level, with the caveat that the middle is likely to be following from the last. Your OOC answers about the world lead to, as
@Manbearcat said
actionable character moments that move the fiction. Without the OOC work up front and along the way, my personal experience is that you don't get much of the middle - just idk, banter? Which is fun and all, for the people involved, but can quickly get spotlight hoggy and boring.
I think the lines blur quite a bit: it's all conversation between the players. What some game texts do is provide prompting, structure, and mechanical consequence. Groups observably can do those things for themselves, but I would say that knowing what to put in place, and judging how it should pay out (such as via the progression system), takes practice and benefits from playtesting cycles.
But it is also down to the group to engage with it. I've observed DW and MotW character bonds becoming for some groups quite perfunctory. Some D&D campaigns as a result of DM curation and player inclination have had far stronger inter-character action going on. Particularly the sort of campaign I would label "political" campaigns. But then in those campaigns I recollect a lot of OOC conversation, as well as IC... and in many cases with the lines-blurred; one segueing seamlessly into the other. I've never experienced much IC talking for the sake of talking, overall.
Stonetop prompts and structures an extensive web of player answers to character and world questions. Referring to
@pemerton's post up thread, one could foresee that to mesh players into the world in a way that develops and strengthens meaning. Their establishing imagined facts and sharing them creates - each to the other - an objective reality. I personally experience that establishing imagined facts and externalising them puts them outside of me in a way that reifies them for myself, but I recall others on these forums saying that they don't experience that. I'm looking forward to playing it, although I'm starting to question my decision to wait until the books arrive.
Reading the last several exchanges on all this, one could assess it as just a question of "how do we want to spend our time at the table"? A preference. Why waste time on a web of relationships if it's performance on the battle grid that you most care about? I personally see play as ever-changing: so that even if we're focused on the battle grid for a few sessions, we'll likely do what we want to with that and move on to interest in emotional conflicts pretty soon after.
At the same time, one could assess it as an evolution of technique that isn't locked to any particular mode of play. A valuable expansion of the techniques available for design and play. I'm inclined toward that in part because of what I have already said about achieving objectivity. OOC steps in play are effective in my experience in establishing that which we can go on to successfully pretend is objective reality. Some may want to argue that it is locked to one mode, which if so should lead to some interesting conversation.