Short answers, pulled from the story.
The Lend-Lease Act was signed into law by President Roosevelt on the 11th of March 1941. It authorized the U.S. to supply Allied nations with food, oil, and military equipment during the Second World War, on the basis that such aid was essential for the defense of the United States itself.
A total of $50.1 billion worth of supplies was shipped under Lend-Lease, representing 17% of total U.S. war expenditures. The United Kingdom received $31.4 billion, the Soviet Union $11.3 billion, France $3.2 billion, and China $1.6 billion, with the remaining $2.6 billion going to other Allies.
Soviet Marshal Georgy Zhukov stated in a secretly recorded 1963 interview that the Soviets could not have equipped their reserve armies or continued the war without American material, specifically citing the lack of explosives and gunpowder. Nikita Khrushchev wrote in his memoirs that Stalin told him privately, on several occasions, that the USSR would not have won the war without U.S. aid.
Britain made its final Lend-Lease repayment of $83.3 million on the 29th of December 2006. The debt had been structured as 50 annual payments beginning in 1951 at 2% interest, with several years of allowed deferrals.
Three main routes carried supplies to the USSR: the Arctic route (3,964,000 tons, with 7% lost at sea), the Persian Corridor (4,160,000 tons, 27% of the total), and the Pacific Route (8,244,000 tons, 50% of the total). After December 1941, only Soviet ships could use the Pacific Route, and only non-military cargo could be carried on it.
The Soviet Union received 1,911 steam locomotives and 11,225 railcars through Lend-Lease, accounting for 92.7% of its wartime railroad procurement. Soviet domestic production during the entire war totaled just 446 locomotives, with only 92 of those built between 1942 and 1945.