Permissions on files created by Linux in NTFS
From the mount.ntfs-3g man page:
When a user mapping file (usermapping=file-name) is defined, the options uid=, gid=, umask=, fmask=, dmask= and silent are ignored.
- In Linux all files and directories in NTFS should be owned by root and have a group win. Permissions should be set to 775.
You don't need a usermapping for this. Your UID, GID and umask settings are correct, just ditch the usermapping=
Point 2. is achieved by using inherit which you already have.