Regarding shells - Mazda 6 and Speed 6 are proven shells for carpet and asphalt racing.
I had R9-F and it was too twitchy. I'm going to try LTC-R soon (I have to paint it
).
DNA shells were designed for foam cars and they have less downforce because foams generate enough grip so I belive that's no way to go as you need more downforce to generate grip.
Stratus should be most neutral shell from those you've got on the list.
Personally I've got only experience from low grip carpet and asphalt - not polished floor - I also belive there isn't any shell designed for such purpose.