NAS device using USB and Ethernet – formatted with NTFS

I’m trying to come up with a ‘low end’ solution for network storage.

I’d like to purchase a NAS device that has USB and an ethernet port. Plug them both in. Use the host PC to format the drive to NTFS in order to use permissions on the drive.

The main use of this drive would be through the network port. The USB function would only be to establish NTFS permissions.

If this works, would the NAS device be totally functional if the USB was unplugged? I have read bits of info about NTFS being read only on a network share. I’m not sure if I understood that correctly.