Short answers, pulled from the story.
The Neutrality Acts of the 1930s were a series of laws passed by the US Congress in 1935, 1936, 1937, and 1939 in response to the wars leading up to World War II. They aimed to keep the United States from becoming entangled in foreign conflicts again after World War I.
Congress passed the first Neutrality Act on the 31st of August 1935, followed by further acts in February 1936, May 1937, and on the 4th of November 1939. Most of these provisions were repealed in 1941 in the face of the Lend-Lease Act.
Congress passed the Neutrality Acts amid rising isolationism after World War I, fueled by the Nye Committee hearings of 1934-1936 and H. C. Engelbrecht's 1934 book The Merchants of Death. Many Americans had come to believe bankers and the arms industry had pushed the country into World War I for profit.
Cash-and-carry, devised by Bernard Baruch and added to the Neutrality Act of 1937, let the president allow arms sales to belligerents in Europe if buyers arranged their own transport and paid in cash. Roosevelt believed it would favor Britain and France, since they controlled the seas.
The Neutrality Act of 1936 did not cover civil wars like the one in Spain or civilian goods like trucks and oil, letting companies such as Texaco, Standard Oil, Ford, General Motors, and Studebaker sell to Francisco Franco's Nationalists on credit. By 1939, Spain owed these firms more than $100,000,000, before a January 1937 resolution and the Neutrality Act of 1937 closed the loophole.
Charles Winters, Al Schwimmer, and Herman Greenspun were convicted in 1948 under the 1939 Neutrality Act's licensing provision after smuggling B-17 Flying Fortress bombers from Florida to Israel during the 1948 Arab-Israeli War. Winters received an 18-month prison sentence and a $5,000 fine, while Schwimmer and Greenspun were each fined $10,000.