Check the screw holes on any 8TB and larger drive you're buying-- the last few years as drive capacities have increased, platter counts inside drives have gone up, and the middle set of screw holes in 3.5" drives has disappeared as a result (there's no longer room for them!).
Seagate, Toshiba, HGST, WD... all current 8TB drives seem to be fine, I'm not aware of any serious defects floating around. For a desktop I would probably avoid nearline/enterprise drives such as HGST Ultrastar or Seagate Exos/Enterprise Capacity as those are usually tuned for performance, not for low noise.
Looks like that Apricorn card is SATA 6Gbps, so ideally you'd use the SATA ports off it it. Power is just an ordinary SATA power cable, I don't remember what kind of power cables are free inside of your MacPro tho so I don't recall what kind of adapters you may need. Honestly if it's just for bulk storage, the SATA 3Gbps ports built-in to the MacPro should be fine, I might consider just using those and not worrying about it.