If other people can see my feedback, can they tell it was from me?
It depends on the cycle settings your HR Administrators have selected.
The default cycle setup is set so that feedback is delivered anonymously, and only HR can see who wrote what. Your team can also choose settings that make feedback anonymous to the recipient but allows his manager to see who wrote what.
When you write your feedback, you'll see a note on the page telling you who will be able to determine that the feedback was from you.