Selfhosted

Hi there, folks. I hope this post is okay here. I'm trying to do my best to follow the rules and also to have done my homework before I come here with questions, but if this is the wrong place to ask my questions, I'd just like to politely ask for directions for the right place to ask. I recently started test driving Jellyfin in a more limited way on my desktop, and I'm impressed. I'm way on board with building out my library and self hosting the majority of my media consumption. I'm looking into buying a NAS, and it's not going to break the bank, but it's still a substantial purchase, and I don't want to waste money by buying the wrong thing for my needs.

I'm looking at getting something like a UGreen DH4300 NAS with four 8 TB hard drives in RAID 5, which ought to be 24 TB of usable space, if I understand correctly. My primary use case is going to be a Jellyfin server for video, though I might try hosting other media libraries and files there like eBooks and such, through Jellyfin or otherwise. Looking at my Blu Ray shelf, I've got about 65 Blu Rays already, some of which are combo packs with 4K and 1080p versions, and once I've got a server like this set up, I'm very much inclined to build that library out even more. Currently, I have no screen or drive with which to watch 4K movies (I have a regular Blu Ray drive, a 1080p TV, and my PC monitor tops out at 1440p), but if I'm being mindful of future proofing, whenever my current TV dies, I'll have more reason for accumulating 4K content. I don't intend for frequent usage of this Jellyfin server to be by anyone besides my wife and me, and I'd be surprised if I ever had 5 simultaneous users.

So here are where my questions come in.

1. Is a NAS like the one above strong enough to drive high quality output to even 5 simultaneous users, rare though that use case might be? Other than my regular gaming desktop, which is quite powerful, I also have a Minisforum EM780 mini PC that could potentially drive a media server if that's necessary/sufficient?

2. I've been reading posts in this community here and there, and I've come across a comment or two about security when exposing ports to the outside world. At the risk of being a big dummy, with selective port forwarding, what kind of real risks are there to this? And is there a reasonable way to navigate those risks such that I could regularly access my own Jellyfin server when I'm on the go like I would any third party streaming service? To be clear, this project is still of interest to me even if it's restricted to my own home network, but it would be a bummer if exposing it to the outside world was particularly ill advised.

3. I've seen measurements of things like decibel levels in reviews and words of caution about power draw, but I'm curious for feedback from folks here about real world noise levels and power draw from a NAS like the one above with HDDs. Is the noise easily ignored when it's in the same room? I have a small apartment, and there are only so many places I could feasibly put one. Is the power draw noticeable on your electric bill such that you're particularly mindful of when it's running?

4. Any other tips for this project that I might not know that I don't know?

Thanks!