NAS / NAS + server? Unraid, Proxmox, Intel, AMD? Looking for guidance.

A LOT of questions there.

Unraid vs Truenas vs Proxmox+Ceph vs Proxmox+ZFS for NAS: I am not sure if Unraid is ONLY a subscription these days (I think it was going that way?) but for a single machine NAS with a hodgepodge of drives, it is pretty much unbeatable.

That said, it sounds like you are buying dedicated drives. There are a lot of arguments for not having large spinning disk drives (I think general wisdom is 12 TB is the biggest you should go for speed reasons?), but at 3x18 you aren't going to really be upgrading any time soon. So Truenas or just a ZFS pool in Proxmox seems reasonable. Although, with only three drives you are in a weird spot regarding "raid" options. Seeing as I am already going to antagonize enough people by having an opinion, I'll let someone else wage the holy war of RAID levels.

I personally run Proxmox+Ceph across three machines (with one specifically set up to use Proxmox+ZFS+Ceph so I can take my essential data with me in an evacuation). It is overkill and Proxmox+ZFS is probably sufficient for your needs. The main difference is that your "NAS" is actually a mount that you expose via SMB and something like Cockpit. Apalrd did a REALLY good video on this that goes step by step and explains everything and it is well worth checking out https://www.youtube.com/watch?v=Hu3t8pcq8O0.

Ceph is always the wrong decision. It is too slow for enterprise and too finicky for home use. That said, I use ceph and love it. Proxmox abstracts away most of the chaos but you still need to understand enough to set up pools and cephfs (at which point it is exactly like the zfs examples above). And I love that I can set redundancy settings for different pools (folders) of data. So my blu ray rips are pretty much YOLO with minimal redundancy. My personal documents have multiple full backups (and then get backed up to a different storage setup entirely). Just understand that you really need at least three nodes ("servers") for that to make sense. But also? If you are expanding it is very possible to set up the ceph in parallel to your initial ZFS pool (using separate drives/OSDs), copy stuff over, and then cannibalize the old OSDs. Just understand that makes that initial upgrade more expensive because you need to be able to duplicate all of the data you care about.

I know some people want really fancy NASes with twenty million access methods. I want an SMB share that I can see when I am on my local network. So... barebones cockpit exposing an SMB share is nice. And I have syncthing set up to access the same share for the purpose of saves for video games and so forth.

Unraid vs Truenas vs Proxmox for Services: Personally? I prefer to just use Proxmox to set up a crapton of containers/vms. I used Unraid for years but the vast majority of tutorials and wisdom out there are just setting things up via something closer to proxmox. And it is often a struggle to replicate that in the Unraid gui (although I think level1techs have good resources on how to access the real interface which is REALLY good?).

And my general experience is that truenas is mostly a worst of all worlds in every aspect and is really just there if you want something but are afraid of/smart enough not to use proxmox like a sicko.

Processor and Graphics: it really depends on what you are doing. For what you listed? Only frigate will really take advantage and I just bought a Coral accelerator which is a lot cheaper than a GPU and tends to outperform them for the kind of inference that Frigate does. There is an argument for having a proper GPU for transcoding in Plex but... I've never seen a point in that.

That said: A buddy of mine does the whole vlogger thing and some day soon we are going to set up a contract for me to sit down and set her up an exporting box (with likely use as a streaming box). But I need to do more research on what she actually needs and how best to handle that and she needs to figure out her budget for both materials and my time (the latter likely just being another case where she pays for my vacation and I am her camera guy for like half of it). But we probably will grab a cheap intel gpu for that.

External access: Don't do it, that is a great way to get hacked.

That out of the way. My nextcloud is exposed to the outside world via a cloudflare tunnel. It fills me with anxiety but as long as you regularly update everything it is "fine".

My plex? I have a lifetime plex pass so I just use their services to access it remotely. And I think I pay an annual fee for homeassistant because I genuinely want to support that project.

Everything else? I used to use wireguard (and openvpn before it) but actually switched to tailscale. I like the control that the former provided but much prefer the model where I expose individual services (well, VMs). Because it is nice to have access to my cockpit share when I want to grab a file in a hotel room. There is zero reason that anything needs access to my qbitorrent or calibre or opnsense setup. Let alone even seeing my desktop that I totally forgot to turn off.

But the general idea I use for all my selfhosted services is: The vast majority of interactions should happen when I am at home on my home network. It is a special case if I ever need to access anything remotely and that is where tailscale comes in.

Theoretically you can also do the same via wireguard and subnetting and vlans but I always found that to be a mess to provide access both locally and remotely and the end result is I get lazy. Also, Tailscale is just an app on basically any machine whereas wireguard tends to involve some commands or weird phone interactions.