New Build for Unraid!

[ExNova]

Hello everyone!

in the next few weeks i'm going to assemble my new unraid server. Until now I have only ever dealt with Windows 7-10-11 so it will be my "first time" with an operating system other than Windows. That is why I have several doubts/questions

I will mainly use the system for 3 purposes:
1- Storage of photos/videos and memories of the whole family
2- Plex Media Server (with tens of TB of Anime)
3- Delegating operations to the NAS that were previously done on the PC such as creating virtual machines, home automation, video surveillance, etc..

 

The build I am thinking of, is as follows:

CPU: Ryzen 9 7900 (not X)
GPU: / 

MOBO: ASUS TUF GAMING X670E-PLUS AM5 ATX

RAM: Kingston Server Premier 32GB 4800MT/s DDR5 ECC CL40 DIMM 2Rx8 (KSM48E40BD8KM-32HM).

PSU: SILVERSTONE SST-ST65F-PT V1.1 650W 80 PLUS PLATINUM

HeatSink: ARCTIC Liquid Freezer II 420mm

SSD Cache: Samsung 980 PRO 2TB

HDD: 2x Seagate Exos X20 20TB (SATA)

CASE: Fractal Meshify 2 XL – Full Tower

 

I plan to start with 2 HDD but will definitely add more in the future (the case supports 18HDD)

 

What do you think of this build? Would you make changes or is it OK?

I was initially aiming for an i5-13500 but then I found out that Intel motherboards don't get along very well with ECC ram, so I switched to AMD. I decided to go with the ryzen 9 for the simple fact that in terms of power efficiency it is much better than its smaller siblings and compared to Intel (I have no idea if I'm actually going to use the 12c/24t but I think it's better to have it than not).
is it true that in idle intel processors consume less power than AMD processors? 
Is UnRaid optimised to use the E-Cores of 12th/13th gen processors?

I am trying to create a build that is energy efficient but at the same time can offer great performance should I need it.

Regarding HDDs, I have heard some people recommend SAS drives when dealing with very large drives because, according to them, they are much safer. is this true? In my country, a 20TB SAS disk costs 50% more than its SATA counterpart. 
I am very sensitive on this subject since I am going to use 20TB disks and therefore, in the future, when they break, UnRaid will have to manage DATA-Rebuilt of tens of TB

As I gradually add disks, I don't think I will use ZFS (I have read that XFS is better in these cases).
A friend of mine who uses TrueNas told me that it is recommended to have 1GB of ram per TB of data. Does this advice also apply to UnRaid or is the SSD enough for the cache? Currently, is 32GB of ram enough? (with 2 HDDs one for data parity and the other actually usable)

 

Thank you very much for your patience.