Your best bet is to have a residential structural engineer do a site visit and a soil test. As the home is only 10 years old, it is normal to have some settlement and additional settlement after 10 years should be minor. The fact you are concerned of future settlement should be a red flag. Additionally, you are concerned about moisture. Two red flags. It is your choice, but buyer beware. Best of luck.

For the dining room, I think I'd orient the table 90 degrees from how it's drawn, and I would make it a drop leaf or gateleg table so that it can be made smaller when not being used for dining. I would embrace the idea that the entry is right in the middle of the living room, and bring the living room furniture out towards the fireplace so the fireplace is connected to the seating area. Maybe TV above fireplace. In that back corner where the sofa is drawn, I'd make that a small work/office space.

Length from the E main entrance to the SW window is 400 inches and breadth from W wall to SE window is 310 inches.

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