A good start for your little hermit, looking forward to seeing how he gets on. :D I would suggest putting down stockpiles immediately, because by default, harvesting and gathering tasks will automatically chain into hauling the produce back to storage if there is one, which saves a separate trip to pick the stuff up later.
Sparks from fires got out, not up. It would almost certainly have been fine to put a Straw Roof over the fire, as long as nothing flammable was adjacent to the fire that could alight.