1 - NAS storage of files and backups, along with running Plex. I don't see Plex being heavily used at the same time, maybe two devices at once at most.
2 - A VM to run 1 instance of Ubuntu. It would be for learning purposes and basic use.
3 - 2 VMs to run an instance of Windows on each one. One copy of Windows would be for in the event a friend comes over and would like to play PC games on this VM. Another VM would be dedicated to streaming content from consoles/my main gaming PC onto Twitch/Youtube with a connected capture card.
I know the Windows VMs require a beefier video card based on their purposes (Ubuntu not so much), but my question is how many CPU Cores and RAM do you think would be required to run it all confidently. While I have an idea of what it would take for the Windows VMs, I'm not sure about the others. Thank you in advance for the help. ^^