A:AnswerIt does NOT come with a SLI or NVLink (newer) link. You would need to buy it. I bought the card last month, upgraded from a GTX1080, I’m playing all games 4K60fps on highest or high detail no problem. It’s a great card!
A:AnswerWhen I was upgrading I found it available during black Friday. It was pretty frustrating to get one as pre-black friday they didn't have any. I think around holidays do they have it.
A:AnswerWith a DisplayPort and compatible 4K monitor it can, yes. CPU does, however, matter very much in this context as hearthstone is not a very graphics intensive game. You could probably get away with a weaker gpu.