Clovis --
I wouldn't dream of getting rid of the lathe and plaster -- it's got a look to it that can't be matched with drywall. Besides which, I hate drywall dust
No, as much as can possibly be retained of the original outfitting will be. The plaster, etc., really is in excellent condition, and for the most part, the hardwood throughout looks perfect. They have laid indoor/outdoor carpeting in the kitchen and mudroom

which will be coming up, so I can't speak to the condition of the floors there, but I'll know soon enough.
The dining room, hallway and library (study, parlor... the OTHER living room on the main floor

) have the most gorgeous carved wooden panelling... and all the woodwork is original and unpainted (beautifully stained) except in the kitchen and bathroom upstairs, where it has been painted white to match the walls. I haven't fully decided yet, but I believe I'll keep it this way in these two rooms. I want "light and airy" in the kitchen, and a white theme in the bath (with the original clawfoot tub).
I can't tell you how very much I'm looking forward to this project. I was a little leary until I realized... I have my very own panel of experts to turn to!!