RE: Clarification tag, yes I believe adding the stones raises a longer hour persistence of the Fireplace and when it's upgraded to an oven. Not too sure on resistance to wind and rain is affected by upgrading with stones but quote from the 1.08 patch notes:
Tweaked: The Stone Oven requires 16 large stones to be built, the stone circle 8 Changed: Fireplaces under exterior roofs will ignore rain and wind factors Changed: The stone oven is immune to rain and wind effects Changed: The fireplace with a stone circle has a lifetime of 2 days, the stone oven lasts 7 days (refreshed by interacting with it)
Article needs to be edited to include change to Oven as well. Bit too tired to do it myself atm. Please include when editing:
Tweaked: The fireplace cannot be ignited in interior space with a ceiling height of below 5 meters Tweaked: Cooking on the long stick is now disabled for the barrel fireplace (new direct cooking slots on top of the barrel are available instead) Removed: Attachments slot for books in the fireplace inventory Removed: Stacking of small and large stones outside of the fireplace