With this amount of money, you really should wait for the Intel 8700K It will have six cores which will only become more and more handy as the years pass.
Fast Memory is a waste of money. I got 3000 memory only because it was about $5 more than the standard memory, 2700.
Why 32G RAM? I have 16G...
Get a large fan. Open your door. Place the fan in the middle of the room and face it toward the door. That way it will clear out the hot air in your room. Works for me.
Looks like with black ops 3 you should disable your hyperthreading.
https://www.guru3d.com/articles-pages/call-of-duty-black-ops-iii-vga-graphics-performance-benchmark-review,1.html
It is not a good idea to use different kinds of RAM together. I'd just go with the 1333 speed and you are ahead of the game compared to the problems you coudl have. Unless you have a 144 Hz monitor, you won't see any difference with a bit slower RAM.