Re: funny odor
My suspicions is that it's just dirt and pet odors that you're smelling. Regardless of what you plan to do for floor coverings, I would highly recommend that you scr-ape stuck debris and remove any carpet tack strips, vacuum the entire floor to remove all the dust and debris, then seal it with several coats of BIN primer (Zinsser, red label ). This will seal odors and stains in and prepare the floor ready for new floor coverings.
I would also be inclined to seal the walls and ceilings with BIN, then top with two coats of a good quality paint. Barring any leaks or mold issues, this will absolutely seal in any stain and odor from previous residents.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!