New Build - Plex + Home Server - using Microcenter Bundle i7-12700K

I currently have QNAP NAS 453Be (4 drives) and I am afraid that it may die suddenly without warning. With growing collection of 4K movies I would like to move to a 8-drive server and it seems DIY is probably a better option.

I have build desktop PCs in the past. My current desktop is i7-2600K and is sufficient for my current needs.

Microcenter is running a good deal on CPU/Mobo/RAM with Intel Core i7-12700K, MSI Z690-A Pro WiFi DDR4, G.Skill Ripjaws V 16GB DDR4-3200 Kit for $350 and I would like to use this as my basis for the server build.

I have Thermaltake Smart BM2 750W 80+ Bronze PSU

I have 2 x 12TB WD HDDs (currently installed in my desktop but not really used) and 4 x 14 TB WD HDDs in the QNAP.

I will probably go with unRAID (ZFS) for the OS and will install Plex Server.

Looking for suggestions in the following area

  1. Desktop Case which can hold 8 3.5" HDDs with easy way to keep the drives cool (using case fans).
  2. CPU cooler
  3. PCIe card to add SATA ports for additional HDDs (the Mobo only supports 6 6Gb/s SATA ports).
  4. Do I need anything else?

I have only done a little reading and think that non-ECC RAM will be OK for my use case.