Yes, you only need a single sata for your SSD (64gb MFC is plenty) if you choose to use an SSD, some just boot off usb flash
The two 850s will each have about 8-12 SATA connectors, plenty to power the risers
CPU/MB/SSD/Risers will use 100-150 watts total
how many risers can I safely connect to one sata port. I heard if you connect too many they will fry the sata connectors.
here are my adapters:
https://i.imgur.com/c0rsSEu.jpglooking at the back of one g2 850w should I do this?:
PSU G2 850w #1
https://i.imgur.com/xh3iz6M.jpgPSU G2 850w #2
https://i.imgur.com/RxcTphu.jpg