Sharing a disk - SAMBA, WebDAV

Technical Support for Routers VPN, DNS, Leaks
1

I want to share a disk via USB. I don't have a static IP.
I have questions:

  1. how to format the disk - fat32, exFAT, NTFS, ext4 ?
  2. for an internal network is it better to use SAMBA or WebDAV ?
  3. for an external network is it better to use SAMBA or WebDAV ?
2
  1. Recommended to format the disk on the PC first and then plug it to the router.
    If you are familiar with Linux, you can use the mkfs to perform formatting in the router SSH.

2&3. Both are OK, depending on what protocol your client device supports.