Sounds like you've done a bunch of research! Since you're using unRAID, setting up your services shouldn't be too difficult.
For your torrents and VPN, there's a few in the unRAID community store - I'd recommend qBittorrentVPN from Binhex - here's the documentation for setting up their VPN-enabled containers.
For Headscale, I don't have any direct experience but unRAID has a decent Wireguard plugin, and should get you up and running in a pinch.
And for your self-hosted services (especially Bitwarden) ensure you're not exposing this on the net, by VPN is the only option I'd recommend. Even so, I prefer to use Bitwarden's hosting with a family plan, for peace of mind and resiliency. It's also much easier for my family.
UnRAID is a great place to start - it allows you to scale cheaply as you need and is easier to fix mistakes. Good luck, and happy homelabbing!
Kind of makes sense - casting is usually a webstream without extra dev effort. I'm not sure if you still can, but I used to circumvent twitch ads by casting from my phone. Not to excuse their shitty behaviour; I gave up on them years ago and started hosting my own content.