As sam said, a capture card can make your life a whole lot easier. in terms of graphics card, if you can grab a 970/980 for cheap or second hand, then go for it. Though they're last gen cards, they should suffice for your needs for a while. You can also opt for the GTX 1060 or RX 480 if you want current gen performance.
Lots of motherboard and RAM manufacturers are adding RGB LEDs to their products. Hell, even SSDs are starting to get them. Simply do a google search for "RGB motherboards" to see a huge list of options available. I personally like the ones from Gigabyte, ASUS, and MSI.
If you have any other questions regarding your build, don't hesitate to hit us up. That's what we're here for =)