Trying to cut 10 cords a winter to heat a house with a fireplace is like pissing in the wind. The vast majority of heat from a fireplace goes up the chimney without heating the house and it draws in cold outside air to feed the fire. With a freestanding wood stove heat radiates from all 4 sides, plus the top of the stove to heat the room, instead of going up the chimney. Plus, you have much better control over draft and airflow to moderate the burn rate. An insert is much better than a straight fireplace, not not as good as a wood stove. A blower should help the efficiency of an insert.
You need to seriously consider upgrading to an insert or wood stove if you want any reasonable chance of really cutting your heating bills. I agree you need a bigger saw, but I'm not sure the insert/stove wouldn't be a bigger bang for the buck. You really need both, plus the splitter. It's a big investment, but a good stove or insert may cut that wood usage in half, or even more.