Leave thanks for someone in order to appreciate extraordinary effort and results. If you write something else, the person receiving the comment can simply delete it. Besides, constructive criticisms and suggestions are almost always best delivered in person.
No. The person sees only his or her Skill Profile, which is compiled from threeor more ratings. They never see the ratings and you don't see their WorkScore unless they choose to share it with you.
Yes, you can revise your ratings every three months. Your new ratings replace yourold ones.
WorkScore let you describe a co-worker's specific capabilities. You can also thank them for a contribution or document specific achievements and rate a wide range of skills. If the person wants your written thoughts about their weaknesses, they'll ask -- but it is not what WorkScore does.
They see any thank you comments and can delete them if they wish.
Yes, just like you will know when somebody rates yours. That way you can tell us whether a particular co-worker is knowledgeable about your work and fair-minded in their views. If so, we count their ratings more heavily.
Yes, the next time they rate your skills. When a co-worker submits a description of your skills (which they can do every three months) you can revise how much emphasis you want that person's rating to have.