I love it from the outside and the idea of this house, but the internal photos are doing you no favours. The kitchen looks nothing like 18' x 9'.
I think it's confusing with the large number of rooms, and text presented offputtingly in a solid block. It needs paragraphs, bullets and headings, photo titles.
I think the fundamental limitation is the relatively small downstairs with no space for a full dining table, if you exclude the annexe. I can't tell from your photos which room is which, but you could consider styling a couple of the middle room floors as living-ish, maybe playroom or dining, and a study with a bed in the corner to help people visualise the options. There seem to be a lot of rooms that are fairly bare with a sofa or futon. But then you wouldn't want dining table or playroom on different floor to living room AND kitchen would you? Hm maybe not then.
If there's potential to knock through I'd be interested to know that. Apologies if that's already in the block of text, I'm afraid I gave up. I know prices are regional but blimey there's a lot of house there for the money.
Sofas lined up against the wall implies the living room is too narrow to do anything else with, but 10 foot wide should be plenty. Are they just the world's most enormous sofas? Could you put them either side of the fire instead, maybe with a table at the other end?