I agree with Judy M. And at minimum, I prefer that the front feet of both sofas be on the rug. But there are many different configurations that work.

I really don't see an issue with the rooflines. Looks like the angles are fairly similar and the clean lines of both structures should be easy to coordinate, especially in your open, rural setting. Since you've found a stunning deal, I would say, go for it! I definitely would want to find an architect ASAP and by all means, before you pour the slab, make sure you have a plan to coordinate.

I read an interesting comment somewhere, where a lady invited a group of her friends over to lovingly point out all the problems they saw (through fresh eyes) with her home on preparation for sale. She said she was surprised at marks and damage that she had lived with for so long she no longer noticed them. We "owner built" a home previously, and when we came to sell 7 years later, we painted the garage and did those jobs that we had put off, and it became sad to finally see her at her best, at the end, when we could have been living in a completely finished home all that time. I read about a lady who decluttered her home, had it professionally cleaned (build clean, or bond clean) and had a professional styler do her home and she realised just how nice it could be and decided not to sell. :) ta

A very simple layout keeping the floor space within the kitchen, the WIP takes up a lot of space with not much gain, The broom cupboard could be moved to the Laundry/entrance, narrow. If the wall has been bumped out to the eaves on the deck side giving an extra 300 depth to the kitchen you could make the island 2700 x 1200 and all drawers. The wall of narrow pantry will hold all pantry needs and more, no deep cupboards to dig into. cheers