Couple items. I have been trying to think of encouraging things to say to the star student this decade.
I have an inlaw who runs ultra marathons. If he doesn't lose all ten toenails on a 'short' 50 miler he feels like he should have tried harder. So kudos for you for even trying those. I am the fat guy at mile 48 sitting on a lawn chair with a cooler of beer beside me wishing you well.
Hall and parlor? If you are in a timber framed hall and parlor (in the lower 48) , with the generous fireplace you have described in the central hall at ground level, you are more or less the ideal candidate to 'get away' with an insert. I don't like inserts. I live in the north half of Alaska, and I buy hundreds of millions of BTUs every year. To me, up here at 64 degrees north latitude, an insert is a poor compromise. In the lower 48 in a hall and parlor, with a south facing front door, central spacious fireplace, and then a stairwell on the north wall of the central hall, you are in high cotton. That house was built to deal with an insert.
Your priority one right now is to pick your top 3-5 units that will fit your existing fireplace, get on the phone asking about due dates and whip out your visa card on whatever is in your top five with a reasonable due date. I am a BK fanboi and don't pretend otherwise. If a BK Princess insert would fit and can be installed in mid October I would be done shopping.
Priority 2 is choose an installer. You are going to need an insulated liner in your existing chimney, and it is going to be several thousand dollars. If you find someone who knows what they are doing but you don't want the installer to meet your teenage daughter, send the kid to do campus tours at like U of Vermont or Radcliff or something.
You DO want a blockoff plate. I don't even own an insert, but I have been active here for several years. I have never once heard someone here say a blockoff plate between insert and fireplace chimney was a waste of money. I regularly hear folks say installing a blockoff plate made a huge difference in the perceived performance of their insert.
Priority 3 is going to be to look at your wood shed again. Average, in the lower 48, is about 4 cords per year. Can your wood shed hold 8 cords? Do you have 8 cords split and stacked? I burn about 8 cords per year up here, and I had my wood (just saying) for August 2022 stacked and starting to season in March.
Your priority one is still to get an insert on order, but while you are waiting for installers to call you back (P2) you can be getting going on your wood pile. If you do have 4 cords of eastern hardwoods split recently as of this weekend, you are not at game over for October 2022 but winter is coming (to coin a phrase) and you are running out of time.
There is a guy here,
@Woodsplitter67 , in New Jersey, who has a passive solar firewood kiln system that is coming up with some impressive results as far as drying east coast hardwoods from standing green to ready to burn (<20%MC ) in one season.
His most recent thread is here:
https://www.hearth.com/talk/threads/solar-kiln-for-hardwoods-part-deux.175875/
I found an intermediate thread here, haven't found his original experiment:
https://www.hearth.com/talk/threads/fall-winter-seasoning-in-mini-kilns.189629/
Also, the passthroughs you are thinking about are effective, but they will give your local fire chief severe heartburn and would probably have to be reversed if you ever want to sell the house. They are good for passing heat from the insert up to the upper level, but they are really really good at facilitating a small trash can fire to having the entire building engulfed mui pronto. If you really want to heat the upstairs from the ground level you want a hall- parlor- parlor- hall floor plan, with the wood burner in one hall and cold air coming down the stairs at the other end.
Good luck and best wishes. You are going to be sitting pretty in Sep 2024.