There's a lot of formerly valuable things in the houses. Antiques, etc. Some might be recovered, but most is already lost.
Yes, probably, but the structures themselves are probably a total loss. Sheet rock more or less disolves in a day or two under water. Wireing, insulation, plumbing flooring, siding, roofs probably all gone.
BE VERY CAREFULL BUYING USED CARS IN THE COMEING MONTHS.