Berryboot is something I wouldn't want to part with, as it is a good alternative to using NOOBs or switching out SDs for each OS. I don't plan on streaming, as I don't have internet... yet. Berryboot's bootloader makes switching btw the 3 OS's easy and I want to be able to run all 3 (Kodi for playing movies from the HDD, Retropie for an Emulator, and Raspbian for tinkering with linux.
Sorry about the specs, I was actually just collecting them, because I figured that would be the next question. I am going to try that site you mentioned, to see if that calculator helps. I will take my specs there and see what it says, but, here are the specs anyways:
Seagate Backup Plus 5TB Desktop External Hard Drive USB 3.0 (STDT5000100):
5000rpm-5800rpm (was not able to find a "for sure" answer)
Archer C7 Wireless Dual Band Gigabit Router (AC1750)8 02.11ac
2.4GHz at 91.3Mbps
file FTP transfers benchmarked at 27.5MBps using the router's USB input, but I would just be using as a network drive, so don't think that matters. Not sure if it is required to use FTP or what the requirements are when setting it up this way. I believe I saw some info that you need to partition and set a bootsector or something.
802.11n 2.4GHz at 75Mb/s
Is there any more info I should be looking for?