Reposting @Schnepper's response here.
Thanks for your questions! We are glad to hear that you are finding Annotation Studio useful!
The answers to your questions are:
1) You are exactly right about how to re-use a text. Simply add it to a new Class, and it is good to go. Don’t forget to add yourself to that Class too under “My Profile!”
2) Annotations made do not disappear. No need to worry about that.
3) We have very basic PDF upload functionality. It’s explained here:
If you have any further questions, please do let us know!