That is false, the 14th amendment stated that everyone born in the United States was a citizen. :)
I might not be right but it was that the colonies should break from Britain and form a new government elected by the common people, basically Britain should break connections with the King
The reason it is impractical is they traders had to go around South America... For example, say New York is sending trade ships to San Francisco. They would go all the way down to the bottom of South America and then all they way back up. By creating the panama canal, it allowed ships to cut through the land and make the route more practical.