Short answers, pulled from the story.
The agreement transferred fifty destroyers to Britain in exchange for ninety-nine-year leases on British possessions. Secretary of State Cordell Hull signaled this transfer on the 2nd of September 1940 after Admiral Harold Stark certified the ships were not vital to US security.
Roosevelt declared millions of rounds of ammunition surplus to authorize their shipment to Britain on the 1st of June 1940 without congressional approval. Legal advice from the US Justice Department stated that this executive transaction was legal despite criticism from antiwar Americans.
The United States gained base rights across Newfoundland, Bermuda, and various Caribbean territories including Trinidad, Jamaica, Barbados, and the Bahamas. Naval Station Argentia hosted the August 1941 Atlantic Conference while facilities like Fort Amherst operated until 1945 before closing by 1995.
Six of the fifty destroyers were lost to U-boats and three others were destroyed in other circumstances before the war ended. Only thirty vessels remained in service by May 1941 after many required extensive overhaul due to poor preservation.
Churchill's advisers persuaded him to support the deal because it marked the start of the wartime Anglo-American partnership needed for mutual advantage. The agreement fundamentally altered the course of World War II naval operations even though he compared it unfavorably to the USSR's relationship with Finland.