The 2950x is really nice. It is a decent step up from the 1950x. But if you are just gaming, then save some money and go with the 2700x.
If you want to do liquid cooling, go with the Enermax Liptech. They have full plate pumps for TH. You can get 240mm, 280mm, and 360mm. I have the 280mm and it does a fine job. So you don't need a 360mm to keep it cool.
As far as motherboard, I have the Asus Zenith Extreme, but it is really expensive. I would recommend the x399 Taichi as it is a solid motherboard for the price.