Pesonally, I think the whole hysteria about mold is a bunch of BS. While it is annoying and can be destructive, I wouldn't worry about it too much.
What you should do is get rid of the carpet and drywall. These are almost ALWAYS a bad idea in a belwo gound level basement. Landscaping and grading outside and adding gutters should help a lot. Having operable basement windows and using fans on low humidity days is also helpful.
Personally, I think sealing the inside walls and floors of your basement is not a good idea, because you will end of trapping moisture inside the walls and floors. I think it would be better if they could breathe.
As far as your legal recourse, talk to the lawyer who handled your closing. You might have recourse against the person or company who performed your inspection. He should have alerted you to this problem.
