English language levels: How can you determine your level?

In this video, Alisha answers 5 questions. - What's the difference between 'error' and 'mistake'? Are these words interchangeable? - Should I say: have you received my message or did you receive my message? - What is the difference between Resign and RE-Sign? Also, compliment and complement? - When can I definitely know that I am at the advanced level? - When talking to teachers, do we say Teacher? Miss or Mr.?