If you're going to install a 2nd OS on your Mac for gaming purposes (where you want as much performance as possible) you might as well just dual boot it with BootCamp.
I've not used this before, but it sounds like it's fast, but you'll still have the overhead of running 2 OS's at the same time.
Nah, for that you really want to use BootCamp (native installed Windows). You can then use Parallels or VMWare Fusion to import it as a VM to be used inside of macOS or reboot fully to Windows to get full hardware performance.
I can recommend Wine (Staging, with the command stream patch) if you don't want to dual boot to run games. It's quite amazing how fast it is now. In some games you can have close to native performance.
I don't think they have accelerated 3D graphics, so probably not. Unless you play 2D games, of course :)
yeah, they don't look to have support for the graphics drivers like parallels does, but for some older games that just need a lightweight Windows VM to run on, it'd be fine. If it gets more active development, I'm sure it can grow, but the idea seems to be using macOS's native hypervisor function instead.