i7-5820K - cpu is ok if you find a good price on it or just want a better overclocker than the i7-6800k. but the i7-6800k should still be slightly faster at slightly lower overclock speeds. 28 lanes can still split to x8/x8/x8 on the asus x99-A II motherboard, to allow for two more expansion cards. if you were concerned about having x16/x16 for top end dual gpu's and/or more expansion slots, you would need a 40 lane cpu and possibly a different motherboard.
Noctua NH-D15 Cooler - the NH-D15S will help with the first pcie slot clearance, it should allow the gpu or another card to go into slot 1. with the asus x99-A II motherboard and a 28 lane cpu, slot 1 gets 16 lanes, while slot 3 gets 8 lanes.
Samsung 850 Pro 512GB - not needed with the 960 m.2, especially if not holding media
Samsung 960 Pro 512GB: OS Drive / Scratch / Project / Render Drive - if not doing lots and lots of cache/render writes, you could also consider the 960 evo. which has lower TBW warranty, but still very fast. if you need more space, you could also consider a 1tb 960 pro or 1tb 960 evo.
GTX 1060 6GB Card (in 3rd slot to avoid heatsink issues) - good match to the cpu for adobe software like premiere, but if doing heavy grading in resolve and using gpu intense plugins you might want to invest in a faster gpu. the gtx 1080 ti would be a good option for heavy 4k grading in resolve, but won't be released for a few months. if you need something now you might look at the gtx 1080.
Seasonic X650 PSU - 650w is very minimum and may only handle light overclocking and one gpu. 850w-1kw is often recommended for more expansion and overclocking.
Good point on PSU and GPU, thank you! Will consider CPU.
Concern - everywhere I have read, a separate OS drive is recommended from the scratch / render drive. Any particular reason for moving away from this standard recommendation? I assume it's because of lower end CPU / GPU?
the reason for moving away from that advice was, its built on old advice when configs had 4-5 hdd's. that was mainly done for speed reasons, but then sata ssd's allowed for 2-3 drive configs, and now m.2 performance reduced it down to one or two. it wasn't based on the cpu or gpu, that would reflect more on the media drive for performance. if your renders are only used for timeline playback and will be low to medium bitrate temp renders, a sata ssd like the 1tb 850 evo would probably make even more sense.
one reason to separate the os/apps drive from everything else would be for drive image backups and restore. that would keep the images smaller and quicker to backup/restore. in your configuration new backup images could be created between projects, by deleting all the temp cache/render files and archiving finished project files, which would only leave the os/apps files for the backup image. another thing to note is x99 motherboards can take a little more tinkering to get them to boot from the m.2 drive than sata ssd...