Hi Michael,
Editing 4K over gigabit ethernet isn’t going to work, no matter what machine you’ve got. The proxies might be okay, but transcoding will take ages, as will the final renders. I wouldn’t bother generating optimized media, it won’t help.
Options could include a direct-attached Thunderbolt RAID, with the NAS for nightly backups… or, if your NAS supports the option, maybe a 10GbE connection using something like this: https://www.sonnettech.com/product/twin10g.html
Your iMac should be okay with the proxy workflow, though I haven’t worked with such a large amount of RED… someone with more experience in that realm would be more help than I can be.
As for the folders – I’d recommend day first, camera designation, then card number (Day01_CamA-01).
Doug Metz
Anode