Very relaxed. The copy test that you must take to demonstrate your grammatical skills is the most difficult part and you should definitely brush up on common grammatical errors beforehand. If you pass and get an interview, it is really just to get a sense of your personality and see if you would be a good fit. Questions are easy and it feels very casual.

Copy editor application entailed (when I did it) a cover letter, resume, interview, copy test. Copy test involves mock headline and grammatical questions. Interviews are standard questions — why do you want to work here, why are you qualified, etc. Interview is with the current night editor and his or her assistant.