You could first filter to a given tracker, select all torrents there en masse, and save some clicks; proceeding with your given steps. Cool! Btw, I use VueTorrent alt UI/ Theme
You want a bridge. Like Jabagram or Emulsion. But there's a limited set of features that will work. For example, reactions or group admin on telegram can't be easily replicated over xmpp. And, in any case, we are talking more about having messages and media on both rooms, on either side, replicated. That way, users on telegram (e.g. your friend) can talk to users on xmpp (e.g. you). Reliability for bridges is not good, there are glitches and messages that doesn't make it to the other side, whichever that is. I'd say you prefer to self-host xmpp with cherry-picked extensions, like snikket.org
Handbrake software supports many. Perhaps AV1?
I don't know which codec should be used to rip but you can pick whatever is in use by the latest and popular uploaders at whichever public tracker you decide on to use for those swarms
Check "green blue" deployment strategy. This is done by many businesses, where an interrupted service might mean losing a sale, or a client forever... I tried it sometime witj Nginx but it was more pain than gain (for my personal use)
Monetization is another secret probably. Ads alone could drive millions on streaming platforms. I don't have idea on public or private trackers, but I guess is also more than what I could win in my life xD but that's probably me just being poor.
As to how, I'd probably use zfs send | receive, any built-in functionality on a CoW filesystem, rsnapshot, rclone or just syncthing. As to when, I'd probably hack something with systemd triggers (e.g. on network connection, send all remaining incremental snapshots). But this would only be needed in some cases (e.g. not using syncthing ;p)
The protocol is called DLNA
There are two options, one is tunneling (e.g. tailscale, cloudfare tunnels, or a VPS either with special software or plain old SSH port forward constant connection). The other option, the most popular answer (I think, influenced by how yoy asked) is Dynamic DNS or DynDNS (e.g. duck, hurricane, freedns, etc.) this second one is like the classic solution.
I have no experience with this, but it might be worth to investigate what Home Assistant has to offer both as a DLNA server and clients (I'm thinking on cheap SBCs in each room..)
I heard conduit.rs has lower memory requirements. Dunno if there's a easy to deploy container tho. Good luck!
Not to flame on anyone, and without reading the details on the specific CVE. But, to share as an advice: this reason is why I prefer keepass + syncthing for my needs. Security for a full blown web app is not trivial and has a bigger "attack surface" than a kdbx file moving p2p through my devices via syncthing.