Short story where a person's name define their nature

I am looking for the title of the following story (or possibly two stories):

I read a short story in the late '80s where people were defined by their names. A man sees a depressed woman and wants to offer her comfort. She has no choice but to be depressed because her name is X. However, before he has a chance to, she changes her name to Y, and therefore isn't depressed any more because all people called X are depressed by nature but no-one called Y is depressed.

I'm not sure if this is part of the same story or a different story but there was a train that travelled through the land collecting passengers. As more people got on board it "grew" more carriages. The people who were on the train stopped being productive, existing in an endless party. A young boy sees through the illusion (a la The Emperor's New Clothes) and starts telling the passengers. Knowing the truth causes the train to start disappearing as it is powered by belief or something like that.