Ответ:

  1. Godfrey Norton was talking excitedly because he was worried that he might be late for his wedding.
  2. They went to the church separately because they did not want anyone to suspect that they were going to get married.
  3. Holmes followed them because he wanted to find out where Irene Adler lived and to discover where she had hidden the photograph.
  4. Irene Adler followed the friends to the house because she suspected that they had been sent to search her house.