After months of delay, Senator Christopher Dodd has offered a fuller but less than satisfactory account of the V.I.P. mortgage loans extended to him by a key player in the subprime mortgage crisis. Mr. Dodd, the banking committee chairman who oversees remedies for the continuing financial crisis, denied any ethical wrongdoing or “sweetheart deals” in the $781,000 house refinancings he got through the Countrywide Financial Corporation.