It was if obtained by fraud, which describes the bulk of his pay, which was in the form of incentives and performance bonuses.
Maybe. There's a criminal conviction on the books, and even if no longer potent as a matter of law, I presume this fact and the details will make ripping good drama in a civil trial, where a lower standard of proof suffices.
OTOH, if by "win" you mean recoup the $217 million dollars Lay made through stock fraud (option sales), or the $10.6 million from performance bonuses and long-term incentives he received in 2001 alone (as alleged in paragraph 16 of the criminal indictment)...not a chance in hell.
Best, James Arthur