The loss of farms, crops and enslaved labor as a result of the civil war meant that the entire nation's economy had to be rebuilt - c. While not all parts of the nation were equally hurt here, it was the case that the civil war brought upon very drastic changes in the way how the country progressed since then.
Because the germans thought it was meant to hurt them and embarres them so hitler use that to his knowledge and told them he would help the germans if they let him become powerful.
The Manhatten Project was designed as a "think tank" to develop the first atomic weapon. The brightest scientific minds were recruited and vetted to ensure that the U.S. had the bomb before other countries.
