It is quite real. The satellite links are like 10 Mbps. You go far enough south, and you cant even hit the satellite because it's over the horizon. There aren't any high-speed polar satellites. Companies don't send their satellites that far south because there are too few customers to justify the cost.
That's changing with starlink, though, since those ones are in a polar orbit.
Edit: yeah I also looked up screenshots. There are a lot of expensive lighting effects in some of those screenshots.
You want a visually impressive game, you're gonna need a GPU that can keep up. If you want to play an actual grayscale game, try The Return of the Obra Dinn. (It's still full 3D Unity under the hood, so you'll need some GPU, but the stylization effects means they don't need to do anything but basic geometry and static lighting.)
Yeah, you'll have to have a bypass list for some sites.
Honestly, unless you're actually on a very limited connection, you probably won't see any actual value from it. Even if you do cache everything, each site hosts their own copy of jQuery or whatever the kids use these days, and your proxy isn't going to cache that any better than the client already does.
Yes, Windows peer to peer update downloads work over LAN. (In theory, I've never verified it.)
HTTP caching still works fine, if your proxy performs SSL termination and reencryption. In an enterprise environment that's fine, for individuals it's a non-starter. In this case, you'd want to have a local CDN mirror.
They're not required if you disable or block them. In an enterprise environment, you deploy a local update server, like I said.
As far as your personal devices are concerned, though, you're on your own. If your iPhone refuses to do something because it wants an update, you'll just have to wait to do that thing until you get home. We don't have the bandwidth to spare.
I've worked in an environment like this. We had a local server for Windows and Mac updates. Direct updates were blocked. It's a solved problem, you just need developers to participate.
Try one of the android communities