No, you can’t make requests to roblox.com from HttpService, probably because Roblox servers might make internal requests that only work when they originate from Roblox servers, and letting you make requests to roblox.com could be a security risk.
No, they already did a while ago.
Yes, but that’s not what the original post is about.
All this means is the mentioned APIs which Roblox uses for what was previously called VIP servers are being removed, and now you need to use the APIs with the other name (which could also differ in some ways but I don’t think they do in this case).
This isn’t any sort of wacky convoluted way just to say that Roblox is renaming VIP servers to private servers or anything, they already renamed them a while ago, this just has to do with those web APIs that might break people’s apps.
Roblox makes some APIs publicly available, you can use them within services that are meant to somehow work with info on Roblox e.g. Discord bots or websites.