It is great for MacOS, and if you are used to MacBook Pro keyboards. I like it because it is really small and sleek. Goes well will with a minimal clean look.
I don't export at 4K for video editing. Runs games at 4K at over 60fps, which is works for me.
Building a hackintosh can be easy if you have few requirements, or really hard if you want everything to work correctly. So just expect to have to do a bit of tweaking and troubleshooting. And don't get scared when something goes wrong or doesn't work.
Booting each OS on separate hard drives is best. Both OSs utilize the EFI partition on your hard drive, so putting both on one disk can cause issues. My system treats each OS as separate and boots in to them from the BIOS without seeing the other OS ever.
RX 580 pulled from a prebuilt Dell system. It has a blower style heatsink which helps expel heat outside the case.
"AMD processors aren't compatible with MacOS" - please search Ryzentosh
Probably better off using an AMD video card for editing in FCPX. The GTX1080 is an awesome card, but still isn't as optimized.