Zoho projects - notes function

Zoho projects - notes function

When I add notes to a certain task (added as admin), who is able to edit or delete the task ? I have tried it as admin and as a user and the button for the edit/delete note frankly seems to have disappeared for some notes assigned by admin.

Also, as the notes attached to a certain task can still be seen once completed tasks have been archived, can they also be deleted ?

What is the threshold limit for the number of notes I can add to a task ?

Also, is there a function where I can export notes to a document file ?