No, you should not connect a GPU power cable to the CPU slot. Use the appropriate cables for each component.
No, you should not connect a GPU power cable to the CPU slot. Use the appropriate cables for each component.
The GPU and CPU cables for the PSU appear identical. It doesn't really matter which you choose. You also have both 4-pin and 8-pin slots available for your CPU.
You're wrong about the connectors. The PCIe and CPU power connectors are separate. The 4-pin option is optional. Simply connect the 8-pin CPU cable and leave the 4-pin unused. Unless you're running an overclocked 3950x, it doesn't affect anything.