I'm so very sorry that you've been dealt this tough hand to play.  I've not read all the replies, and I debated quite a while before I decided to join in.   We walked a very similar path with my dear dad after he was diagnosed and we lost him in June of 2004.  He had an arterial stent implanted and had the lower lobe of his right lung removed prior to radiation.  Chemo wasn't an alternative for him as a treatment, but his oncologist chose to give him Avastin off-lable to help with his respiration late in the disease process.  It did help and made him more comfortable toward the end. 

I can't answer any of the financial questions you've posed.  It seems to me that a lot of that might depend on how actively involved your wife has been with the farming operation in the past.  If she's not used to dealing with those kinds of things, it probably will be a heavy burden for her to deal with.  If she's always worked with you on the farm, it might not be as intimidating.  I simply don't know.

I think I do know one of the things I would do if facing your situation.  In most midwestern communities it's pretty much traditional to have a visitation or viewing the evening prior to the funeral service.  Instead of doing this, I think I'd have a get-together now, while I felt fairly well.  Something along the lines of not sending flowers when I'm dead and can't enjoy them; send them now and let me savor the beauty. I think I'd like to see my friends and family in an atmosphere of happiness and compassion and everyone has the opportunity to say the things that need said.   Chances are there's a community hall that could be used rent-free if the management knew the reasoning behind it, you could provide the meat and folks would more than likely be thrilled to bring a covered dish to pass.

Just my thoughts.  I do wish you the best, and my thoughts and prayers are with you in this journey.  God bless.