So there are 28x PCIe Gen 5 (24 usable) 16 lanes for GPU, 4 for m.2 and 4 shared with chipset
Additionally 12x PCIe gen4 and 4 Gen3 lanes.
All ssds are running in x4 mode
PSA encodes are one of the best for popular shows and movies. Just give it a try. Generally their encodes is to be consumed as it is and 4k versions might not work with some devices since they only give HDR10 and Dolby Vision encodes. If you intend to watch it with media server with transcoding better go with QxR
WD is boot drive and remaining are for storing AAA titles. They gets full but I uninstall games after completing it but most of the time they are filled to 70-80%.