they built camps in order to increases what they call the 'master race' and to fit in with Nazi philosophy and nazi life, they basically wanted to keep their 'master race' clean and pure, wince there were so many of them they killed a bunch to speed the process up, they rounded up many thousands of communists, socialists, church leaders and anyone else who might oppose the Nazis. and sent them to the camps. at first the holding place for them was local prisons but there wasnt enough space to hold them and that system was inefficient the nazis found a solution by establishing a large camp to hold the prisoners that is why they built them.
A. is because Bilbo does not want to go on an adventure until he realizes he needs to do something other than lay around inside all day long by himself.
