re: Any benefit to not accepting FEMA money?

Accepting the FEMA assistance related to property damaged associated with flooding will typically require you to maintain flood insurance on the property in perpetuity along with agreeing to a permanent deed restriction requiring the same for any subsequent buyer.

The disclosure requirement has been discussed already.

Don't freak out about the Flood Insurance Requirement. You will more than likely remain in whatever zone you were in previously (X-zone for example). Which makes the insurance much more palatable (think a few hundred dollars annually) and won't add to the annual cost of home ownership in large measure.