So for letters you don't indent each paragraph?
Do you need
此致
敬礼!
for an email to a friend?
Can someone who does the course reply? For paper 1, at the end, you are given a passage and a written task of 120 words. It may ask you to summarize the passage but I recently saw a question asking you to write an email. Since emails are informal, I don't know how to write it.