I'd recommend 4x8GB over 2x16GB since X99 has quad channel memory capability. As-is you would get dual channel. Since the board has 8 DIMM slots there's no problem with upgradability if you start with 4 DIMMs.
I'd also suggest staying away from Seagate drives. WD seems more reliable, but that's partially my experience and partially data I've seen from reliability studies. HGST also does well but I have no experience with them.
The PSU is probably overkill - the CPU uses 140W max and the GPU is 150W - that's 290W plus drives and RAM. Figure 320W as an absolute peak, and at 65% load you'd ideally want about a 500W PSU. If you want to add another 1070: (a) do that now, not later and (b) that bumps you up to about a 750W PSU since 320W -> 470W peak load. If you throw some OC in on the CPU, you could figure 200W there but you would want a higher end cooler. The Evo 212 is great for the i5 chips and the mainstream i7s because these are 65-84W parts; the high end i7s are 140W parts which means their stock configuration is already as demanding as an overclocked mainstream CPU.
I'm not an expert on thermal paste but IIRC Gelid GC-Extreme performs slightly better.
I'd also suggest a WiFi card with 802.11ac ability, though if you can run a LAN cable and use a wired connection that would be the best solution.
You also need to be really careful with those fans. The AF series are good for airflow *only* when there's little pressure. Put that fan behind a piece of filter and you can expect the CFM to drop. Typically I would suggest the SP140 over the AF140 as it's likely to produce a greater CFM in the real-world. Also keep in mind that while each fan is ~25dB, when you have 5 identical sources it increases by 7dB (10 ln(5)) so this is 32dB - still quiet, but not like 25dB.
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