Joplin server info before installation

Hello all,
I'm using with great satisfaction Joplin on desktop and several clients using an old NAS with webdav protocol.
Now I added to my network a new raspberry pi 4 model b and I added a 250gb ssd storage to it.
I don't know anything about linux, but with AI I managed to set it up and now it seems to work.
I had to use the raspberry pi as subnet router (using Tailscale) since my FWA router is behind CG-NAT and I can't reach it from the internet. But with Tailscale I can connect to it from everywhere in the world the same way as my local network.
So, I think I'll install Joplin Server on the PI and transfer my notes from the NAS to it.
Here are my questions:

  1. is Joplin Server faster to sync notes than webdav?
  2. actually I created different webdav folders for my family users. Every member has access to his notes separately. How does this work in Joplin Server?
  3. how to move all my notes (10+ GBs) to the Joplin Server?
  4. is there any documentation about Joplin Server (i.e.: user management)? I can't find it (except on the forums)
    TIA
    tony