One of my relatives uses an open fireplace for heating during the winter,
using a mixture of coal and wood. The wood is effectively free. The
fireplace doesn't seem to produce a lot of heat, and I've read that a
woodburning stove might be much more effective, by virtue of drawing less
cold air into the house and sending less heat up the chimney. I have some
questions:

The regularly-swept chimney copes fine with the mixture of wood and coal
burnt in the fireplace, so is it likely be be OK with a wood stove, if
suitably connected? The house is about 20 years old.

The house is in a rural area, but there are a few houses nearby. Is the
exhaust from a woodstove likely to cause more nuisance to them than that
from the fireplace?

An ideas where I can get a cheap stove? I'm hopefully monitoring my local
Freecycle group, but I guess recent energy price rises have made wood stoves
very sought-after.

Any other things worth trying?