Hi Jo, here are 2 great pages for high key explaination:
I was taught that the only time we need to worry is when we think that we don't need constructive critiques.
Now, as to those who are just learning art? I don't think that critiques should be used at all. Just kudos on the parts that they did right and explain why you think that they did good in a certain area. If they then ask, "how about that area?', then tell them how they could fix that but letting them know that is not the only solution and only an opinon..
You explained what each critique was to the letter.
You're a smart cookie. ;D