So, with the DDR4 memory in the list, I guess upgrading piece by piece will not be possible since I currently have DDR3 and I've heard that DDR4 and DDR3 cannot be combined.
With your reply, here are some of my inputs:
CPU: i5 6600 (Final)
GPU: GTX 1060 6GB (don't know which brand yet)
MOBO: ~...