I’ve been self-hosting a wide variety of things including nextcloud (which is one open source project I advocate everyone look at, especially on a web domain so they can access it from anywhere)
Go linux for hosting your open source projects. Just do it. I’m not saying that because windows is inherently worse than linux, but because everything out there is documented as if you’re hosting off of linux. In fact, you should really consider using Ubuntu-server, because most things have documentation specifically for ubuntu.
Going with windows server as mostly just s hyper-v box with your linux installations inside, that might be worthwhile.
If your IP address appears static, then you can probably just directly configure dns through the web interface of your domain provider. There’s a great script out there for doing dynamic dns using different providers such as godaddy, that could be some insurance to make sure you don’t end up with a non-working social media network.
One thing you should consider is running one virtual host as your reverse proxy that redirects different subdomains to the different individual servers running your services. The reverse proxy server running something like nginx would then deal with all your subdomains, and if you work on say your nextcloud and need to reboot it won’t take all your services down at once because your reverse proxy continues to function for all your other services.