I have a single application/service that I need to run on Windows. It will serve as a public application, kind of like a webserver (users connect to it using a browser), and needs to server up to hundreds of (web)users. Further the application uses a MySQL database.
First I found Windows Server Web, although it felt a bit too much only aimed at IIS (which I don't need?). But later I found Windows Server Foundation which looks like fit for the job.
I question a bit if I can serve a lot of webusers with it. It says to limit to 15 users, but I guess that is about actual users on the Windows system, and I think the webusers are more like 'connections' for Windows?
Further I noticed that it doesn't support subdomains. Does that mean I won't be able to set it up with a sub.domain.com or that I only won't be able to that when I also want the domain.com on the same server?
Are there any other limitations I should keep in mind? Or should I go for another server product?
What you are trying to do is illegal. Forget this "cheap" server. Get SPLA signed (Service Provider Licensing Agreement), rent Windows Server Web Edition for a REALLY low price per month. No long term commitment and you are legal.
http://www.petri.co.il/introduction-to-windows-server-2008-foundation.htm
Makes no mention of subdomain limitations. If the limitations that you identified are with web sites under IIS or through Active Directory configurations, the you are probably fine as you identified that your application does not make use of IIS and Active Directory does not appear to be a consideration and/or requirement either.