I saw your earlier post including the PDF, and I'm surprised the builder put the stairway door in the kitchen. I was expecting it in the living room, giving you much more usable space in the kitchen. But I like your setup, I'm a fan of smaller living spaces and everyone needs a place to start out (and end in, although those stairs wouldn't work for me).
I like your stove location between the windows (watch the vent code distances). Stove blower will move air toward kitchen door, and big room will be toasty. Kitchens usually heat themselves from cooking
. I would cut a 1sqft vent opening in the wall separating the living room and the stairwell. Put it high on the wall so it is not blocked by the open stair well door. You could add a fan into this opening to help move the heated living room air up the stairs. If you are really krafty you can control this fan with a linevoltage thermostat mounted in the upstairs hallway, between the bedrooms.
I would forego the registers in the ceiling feeding any bedrooms. It permits too much noise and compromises privacy, it also is a safety issue because smoke could easily pass into a sleeping area. Don't forget to add interconnected smoke and CO2 alarms in the living room and upstairs hallway, so you are woken before anything can get out of control.
Lastly, and the original reason for your post, your space does not call for a large stove 50-60 Kbtu. You can pick up a 35-45 unit and run it manual at low to medium all day long. That's about 1.5 to 2.5 lb/hr pellet feed rate, or a continuous heat output of about 9K to 15Kbtu. Anything more and you won't be able to sit in your living room.
If you do a quick calc on the amount of BTU's your oil boiler presently moves into your home (140 kbtu/gallon times about 0.8 efficency times the number of gallons over the number of days). You can look at your summer usage to approximate the DHW portion, and subtract that out. I think you'll find that a space heater running at 9-15kbtu/hr will significantly cut your oil usage. And your GF will be much happier in a warm home (I know of which I speak
, they are all the same on that issue).
Good luck.