Is there any way to restrict user to edit tasks and delete them in his
Tasks folder using addin?

I can restrict single task deletions (when user presses delete button
in task form) using ItemEvents_10_BeforeDeleteEventHandler which has a
reference parameter - cancel.
However I am not able to do this when user select multiple tasks and
deletes them. In this case I can only catch
ItemsEvents_ItemRemoveEventHandler and it has no parameters at all.
Besides, I want to restrict user to edit any of task fields.