Can you help with my first mining rig?

Hi guys, I'm new into cryptocurrencies (I know some basics and stuff) and I would like to start mining some
This is a rig that I came up with, but I need someone who knows more about mining to tell me if this rig need any adjustments. I also need help with motherboard.

Motherboard: I need help with this one.. This is what is available in my country (price from high to low):
Can someone tell me what would be my best option for motherboard?
GPU: 6x AMD Radeon RX480 Powercolor Red Dragon 8GB DDR5
CPU: LGA1150 Intel® Celeron® Dual-Core G1840
RAM: DIMM DDR3 4GB 1600MHz Kingston HyperX Fury Red CL10, HX316C10FR/4
SSD: SATA3 128GB Transcend SSD230S 560/500MB/s
PSU: 1200W Raidmax RX-1200AE-B Modular 80PLUS GOLD, PFC/13.5cm/black
+ 6-Pack PCIe VER 006 PCI-E 16x to 1x Powered Riser Adapter Card
+ Holmes HBF2010A-WM 21-Inch by 4.5-Inch Box Fan

Q:
How many powered riser adapters I will need for that certain motherboard?
Do I need more power supply? (this one is 90% efficient)
Do I need bigger ssd, or hdd?
What OS should I use?
And can anyone tell me how much can I earn (approximately) per month with this?
(My cost per kw/h is $0.05744)
Is this good mining rig? All of this is about $2200


Thanks.