I don’t have any links on hand, but there a post either in this community or !piracy@lemmy.dbzer0.com that explains how to setup a full arr stack in docker. I’ll see if I can find it in the morning.
Here’s a quick and dirty explanation for your other questions. Sonarr and radarr manage your media. Sonarr handles TV, radarr handles movies. That is the only difference. Without a download client (e.g. qBittorrent) they don’t do anything. Jellyfin is how the downloaded (qBittorrent) and managed (*arrs) media gets played on your screen.
I’m foggy on the details, but jellyfin has specific vulnerabilities that make it not recommended to expose publicly. If you must watch remotely, set up a VPN. If you don’t to manually setup wireguard you can use tailscale, which itself uses wireguard, but it does the hard part for you
Surprised the 9060XT 16GB hasn’t come up yet. A quick check on eBay for me shows mostly $300-$400, but saw a couple in the $250-$300 range. If you can find one in your budget that’s my recommendation, otherwise I agree with everyone else on the 6700XT