using mac mini on windows display?

As I said, you can connect the Mac Mini to the PC monitor without any issues. Windows has nothing to do with it.

Its a direct physical connection to the monitor itself and you can switch the connection as you need.

There are also KVM switches that allow you to use one set of Keyboard, Mouse and Monitor, with 2 or more computers (Mac and PC), and switch among them on the fly. Windows again is not involved.

If your PC is an All in one type of design (not a separate monitor) there is to my knowledge no support on Windows to receive video from another computer Mac or PC and switch between video sources.

You can use any USB keyboard with a Mac Mini. The Windows Key will act like the command key.

As far as the display goes, if you mean a monitor, as long as it supports the resolutions provided by the Mac Mini, and has a connection that can be used with the Mac Mini, you should be able to use the monitor just fine.

Yes.

https://www.tuneskit.com/ibook-tips/read-ibooks-on-windows.html

You can use software like Teamviewer or LogMeIn if you want to open a session to your Mac from Windows if that is what you mean.

TeamViewer Mac Download for Remote Desktop access and collaboration