I don't see any problems with your EFI. I don't know why you are not seeing any output devices.
Please try clearing NVRAM at the OpenCore boot menu.
Also, please enter the following in Terminal and post the output:
I don't know why it stops booting. I've never come across this.
Yeah. OpenCore always pops up on top for me too.
I don't know about 3 monitors. I only have one. What sorts of instability are you having?
The boot arguments should work but I've found the USB ports kext works best with OpenCore.
Is what easier? You can either unlock the CFG via (1) Grub or (2) with one of the beta BIOSes. Personally, I like the beta BIOSes because you can also disable serial port. Both are pretty easy, in my opinion...
The only issue with the beta BIOSes is that some people may experience black...
Black screen after updating to one of the beta BIOSes is a pretty common occurrence.
Things to try:
Connect your computer to a TV.
Power your monitor off and on.
Try a difference connection (i.e. HDMI instead of DVI-D, vice versa, etc.)
I don't think so.
I doubt it.
I doubt it.
I don't think Catalina or Big Sur will make a difference.
None that I can think of.
Are you using HDMI to connect your monitor?