Does the processor comes with a cooler? If it does then you don't need aftermarket cooler.

Try v007 or v008 riser instead of riser that use sata to 6 pin adapter

You only need 4gb of ram

Never tried that psu not sure if you have enough connectors, make sure you have 6 x 6+2 pcie cable, 2 sata or sata + molex in 1 cable, you need 3 of those cable to power up 6 riser, it is not advisable to power riser via sata or some might say do not power more than 2 riser.

You need a ssd or you gonna run your OS via usb drive?

You didn't not mention what types of gpu you are getting, so not much advise can be made on psu.