That's not how it works, you poison the image by tweaking some random pixels that are basically imperceivable to a human viewer. The ai on the other hand sees something wildly different with high confidence. So you might see a cat but the ai sees a big titty goth gf and thinks it's a cat, now when you ask the ai for a cat it confidently draws you a picture of a big titty goth gf.
Yeah basically this but where the concrete slab is shown, install whatever flooring system you want. All though I will say a concrete slab will last the longest.
I would dig it down a bit, put in some fresh gravel base and put foam panels over the top. Install a subfloor directly over the foam and flooring on that, with an access panel for the clean out.
Imo this community should have you covered for items 1,2 & 4. Item 3 maybe; but we all do stupid things sometimes. It's part of the learning process.