yes
High Sierra or Mojave
16 GB
leave
No, your research is correct, the 2011 mini's latest (officially) supported macOS is High Sierra. There are ways to install Mojave, but they include modifying the installer (http://dosdude1.com/mojave/).
You will want to create the installer on the USB drive:
Create a bootable installer for macOS - Apple Support
You can use a USB flash drive or other secondary volume as a startup disk from which to install the Mac operating system. These steps are primarily for system administrators and other experienced users who are familiar with entering commands in Terminal.support.apple.com
...
EDIT- never mind I figured it out and added High Sierra and it’s running perfectly.
...
i Was connected with wifi this whole time and just turned it off and ran Ethernet directly to it and still getting the error.
Sorry for all this and I really appreciate your help!
1.So I’ll have to get a USB and download an OS to it then boot it from there?
2.Which software should I use and how big are they typically because I have to buy a new USB that can hold it.
3.Should I change the date back to normal or just leave it?
4.If I have to change it back, what numbers do I input for today?
thank you so much again