ASRock H110 pro BTC+ is the current best mining motherboard for rig density IMO. Very easy to get going out of the box. Since the slots are so close, you do need to cover the back of the riser x1 connectors with electrical tape to prevent them shorting out on the USB connector of the one next to it. Sapphire Nitro+ RX 580's are the best cards in cost/hash for Ethash and are excellent dual mining cards that run cool. 30+ MH/s ETH + 850+ MH/s DCR @ 130-140 W dual mining after a simple Polaris Bios Editor 'one click timing patch' Bios mod.
The very long answer... shortened!
Very well done. Stick to these info.