Currently in my company we have public folders with a few Public Calendars. Users can edit/modify items in the calendars. I'd like to find a way to make sure that users can accidentally move the calendar from one folder to another by accident. Is there a permission that I can set to stop this?

It is pretty easy to do that if you have an item selected when you drag the mouse to another folder. I do that to my mailbox all the time (sometimes dragging the entire folder to another folder). One way to reduce the risk of this is to make sure that a useronly has permissions to folders the absolutely need. That will prevent them from copying items in to folders that they don't have permissions.

Thats the tricky thing. For most of the public folders users need the ability to create and add things to the folders. Sharepoint will probably be a better solution as you can integrate these things into it.

Its very contradictorily; after granted minim Create Items permission, users can copy their items from public calendar, we cannot grant more less permission on that Per my knowledge, theres no default feature which can do the task on the exchange server