It looks like there are some good answers gere, but I'll throw in my two cents.
When it comes to flooding in the basement (or any other issue) the seller is disclosing issues they are aware of. My grandfather passed away in 1979, and after that my grandmother never went done the basement. When she sold the home there could have been four feet of standing water down there and it wouldn't have been on the disclosure because she wouldn't have known. The property having been used as a rental has no bearing on the present value or use and I don't think that's even on the disclosure form. For the pool, if you can get the name of the company that closed it down, they may guarantee their work, but don't count on it.
Your agent may have represented you if you signed a repesentation contract, and he may have represented the seller as well. But his expertise lies in the buying and selling of real estate, so he may not be an expert in waterproofing, rental history, and pool care.
I would hope you hired a home inspector before making this purchase, and if the inspector missed the evidence of flooding, or problems with the pool plumbing, you may have recourse with the inspector.