I was about to say the same thing; the fireplace with the round hole has been converted for a woodstove at some point. That's much, much more efficient than an open chimney fireplace like your other one.
You'd probably need to move that baseboard heater, and the stove should not sit directly on the wood floor - some sort of heat shielding like tile, though it doesn't have to be anything more than a "pad" for the stove. It will take space - it also needs safe clearance from the wall. But cheap, efficient, and yes, might do the whole house. Might cost less than your current heat without any emergency, in fact, as your primary heat, perhaps supplemented if it doesn't get to all of the rooms quite as well.
Again, let me suggest you talk to the local agricultural extension office. They'll be able to give you pointers about either a stove or that wood-burning fireplace (in a bedroom?) and recommend someone in the area to inspect and probably clean the chimney (don't skip this).
You'd have to keep the little one away from it, of course, but that goes for any fireplace or stove.
