1: Just because they can get to 5GHz doesn't mean they perform better. Intel CPUs have a better IPC. They perform about twice as better at the same clock speed in single thread processes like gaming.
2: On the nVidia side I'd recommend a 970 or up for 780Ti performance. If you're willing to do AMD, the 390 is a great choice.
3: Not really a question.
4: Why would you want to? I mean you can, but why?
5: Follow your posts so you can get notifications when someone replies.