Could I pick peoples brains on how they implement NTFS permissions so that for a shared folder, a group can't create random folders or files in the base of that folder, but can read/modify any files ...

What a Linux root user can do - and 8 ways you should absolutely never use it ...

Ubuntu, like other Linux distributions, restricts access to files and system settings by default. Each user account has read and write access to its own files and read access to some system files.