You think the ad is really selling the stove up? So you think the stove will be fine? The only other stove they had was one made by US Stove Co that was only 950 sq ft but like I said my dad said overkill is better than it not heating properly.Some good answers on here already. Yes, you are correct, you need to burn it hot. Small fires will not work, except that you can burn a small amount of wood hot and let the fire die out. You will have pretty wild temperature swings doing it that way berceuse you have light (350 lb.) stove that will heat up quickly and cool off quickly. You might need to crack a window to keep the temperature comfortable on mild days, but that's not the worst thing in the world. The worst thing is NOT burning the stove hot and clogging your chimney up in two weeks or having a chimney fire.
You could probably keep your 850 sq. ft. house comfortable through the winter with 30,000 BTUs, so most wood stoves will be too much, unless your 1930s house is a lot draftier than my 1930s house. The data on the tractor supply website is fairly suspect, but it says the stove can run 40k - 60k BTUs, so maybe it's not as bad as you think. Ignore the sq. ft. numbers. A fairer estimate is 3-4 BTUs per cubic ft for primary heat for this part of the country.