Senior U.S. Official Reads Out Formal Text Of Iran MOU; Says We See Iran In Advance Of Signing Ceasing Efforts To Cut Off Traffic In Strait Of Hormuz; Iran Is Stating That It Will Destroy Enriched Uranium Stockpile And How It Will Be Done; If We Get To A Final Deal And If The Iranians Behave, We Will Permit Sanctions Relief; Iran Is Agreeing, At A Minimum, To Destroy Its Enriched Uranium Stockpile Through Downblending