Jellyfin Server Help, hardware, cache drives, etc

Recently I have started getting back into hosting media and trying out Jellyfin. While trying to stream to my Living Room TV I realized that my hardware is not up to task. Existing server is an old Dell XPS platform with an i5-2300, 8GB of RAM. I added a PCIe to SATA adapter and now have 6 disks in the array, 1 parity and 5 data drives running unRAID Basic license (I'm at 6 disks so I'll have to upgrade this to add any more). I have acquired a Dell Precision 3630 with an i7-8700, 16GB RAM, a Quadro P1000, and a 256 GB SATA SSD. I also have two other 256GB Sata SSDs hanging out in older laptops that I am considering using for cache drives.

So this is really a multi-topic post, which may or may not be the best way to try and get help but here goes.

I'm using the *arr apps and Jellyfin so I'm considering using the cache drives (up to 3 256GB drives) to help speed things up along with the new hardware. I was thinking of using one of the drives to hold the appdata/Dockers. What is the best way to add the cache drive and move this data to the cache drive? The other 2 drives I may use as cache drives for media downloads, but I don't download much right now. Does it make sense to use 2 drives? RAID 1 for speed or something else?

When first testing Jellyfin on my living room TV I wasn't able to stream a ripped bluray without stuttering using the Jellyfin client directly on the TV, a Sony Bravia XBR55X810C. I thought the issue was the server since the hardware is older. But after making a change in my router to give the TV high priority I was able to test stream even a 4K file for a few minutes without any noticeable stutter so maybe the older hardware was OK for this after all. I have not upgraded to the newer hardware yet. I still plan to use the newer hardware as it will just perform much better than my existing hardware for all tasks. I notice that just scanning media in the *arr apps brings the existing system to its knees. Is the 8700 enough by itself to do the streaming and all other server related tasks? Use quicksync? Try it without the P1000 first? Is there any special setup I need to do in Jellyfin or anywhere else if I use quicksync? How should I set up the Jellyfin settings for both server and client to get the best experience? I also noticed that I was only getting 2ch audio to my receiver through ARC from the TV so I need to figure that out as well.

Forgive me if all of this sounds trivial or sporadic. I'm just starting out on trying to figure this out and I think I might be trying to do too much at one time maybe? At the same time I don't want to have to undo a bunch of stuff down the road that I should have done from the start. I might not even be asking all the right questions.

Thanks for your time and let me know if you need any more information.