1) Which does refer to the company. You can't simply omit 'which' but you can replace it by 'that'.
2)Wrong. 'He moved to a city I have never heard of', or, 'He moved to a city whose name I have never heard (before)', or, ''He moved to a city the name of which I have never heard (before).' I am using 'heard' because it is in your original sentence, but it isn't clear whether you didn't hear the name, or whether you had never heard of the city. They are not the same thing.