Windows 8 personal document folder is automatically shared?

I must be outdated. I didn't pay much attention, but found my personal document folder is shared automatically in windows 8. I want to know why this is shared and why there are so multiple sharing options each folder has. I work in domain environment, and recently started using widnows 7/8. This is my home computer having confusion about sharing.

1. When I right-click on Documents folder , then properties windows open.

2. In sharing tab of properties window, there are two sharing options;
Network File and Folder sharing shows my Documents folder is shared.
Advance Sharing is disabled.

Why is my Document folder is shared automatically and what is difference between the two sharing options? I have used mostly advanced sharing, but I can not disable Network sharing of the folder, so I can't do advanced sharing.

3. On the properties/security/advanced window, there's another 'share' tab which shows Everyone has full control besides administrators.

Why everyone has permissions to share my personal Documents folder automatically?

Why is the use of public folder if my personal Documents folder is shared automatically?

Thanks many.