Originally posted by Limited Instruction Set:

I put a campfire right outside one door, bed next to wall inside, no problem.
Not my favorite solution, but I've only just started playing.

Campfire on the bare ground inside the building, make a chimney around it up to the roof to channel smoke, make a gap with pillars to let the smoke out, put a roof on that. At the bottom of the chimeny do make a total frame around the fire so you can't accidently walk into it.

I put a campfire right outside one door, bed next to wall inside, no problem.
Not my favorite solution, but I've only just started playing.

I usually put up a small roof from the exterior walls and put a fire under it and put my bed inside next to it

fire auras work through floors

Near enough you see the buff icon from it.

Probably. Later when you have access to the bonfire definitely.
Remember to put a roof over the fire so it doesn't go out in the rain.

Mine is 5 floor tiles.