I can confirm that the GTX780 works. You will need to install the nvidia web drivers after macOS installation. Tried even using it with tensorflow.
Regarding your first question: I have tried virtualized and bare metal macOS (hackintosh) and I would recommend not virtualizing it if it's gonna be your primary workstation. Currently my main workstation is a hackintosh after trying first using it in a VM.
Virtualizing works, but under a VM there are several minor annoyances here and there that might drive you crazy (most of them are UI related, some app crashes, etc.). It would be perfect for example for a xcode build server. thought. YMMV!