Yes. This is precisely
@Campbell's point. Skill challenges are more freeform than distinct subsystems for exploration, crafting etc - because the structure can be applied to a very wide range of non-combat situations, with the time involved being vary variable, the actions declared constrained only by player and GM sense of the genre/tropes and the fiction, and the resolutions being whatever the GM thinks (i) honours the successes and failures rolled and (ii) fits with the unfolding fiction.
Yes.
@Campbell has drifted away from a preference for 4e-style freeform (eg skill challenges) because of a preference for structure.
For similar reasons I would expect that Campbell would prefer PbtA systems to (say) Burning Wheel or HeroWars/Quest - those latter two don't generally use specific structures to determine specific consequences but rather (very much like 4e skill challenges) rely heavily on GM extrapolation from the fiction.
This is an example of structured resolution, it seems to me. And to me it doesn't seem especially well-suited to dealing with the sort of action I described in my actual play example. And it seems to rest on an "adventuring"/"downtime" contrast that (i) is not core to how I approach RPGing, and (ii) draws the line in a different place from where it might be drawn. For instance, MHRP/Cortex+ Heroic uses a distinction between action and transition scenes, but transition scenes encompass elements of what 5e would classify as "adventuring" (especially but not only travel), and can involved resource management just as much as action scenes (the relevant resource being "plot points", which can be spent in either sort of scene to enhance outcomes).