I use a Synology locally and have great results with NFS. Can’t comment as to the remote aspect as that’s not a heavy use case for me, but there are guides.
Suggest you enable at least one of the options in #4 to facilitate #2.
The way Infuse currently works, watched status is title dependent, not source dependent — so if you back up your watched status to iCloud, it should carry over to your newly created library when you’ve finished downloading everything to your NAS and sync.
if your router do not support ddns, and u hav a public ip address from your internet provider, u can type your ip address each time before u start, but it will cause a re-scrapping of the metadata each time or
2.1. install docker “DDNS-GO” on NAS
2.2. register a domain address
if you don’t have a public ip address
3.1. install docker “DDNS-GO”
3.2. install another docker for Intranet penetration
3.3. register a domain address