Your biggest potential bottle neck is if your NAS and App server only have a single 1g network port. This may not be a problem depending on your usage, but it is a important consideration to keep in mind.
You don’t want hardware raid. Some options you can research:
Some OS options to consider:
There are probably other software/OS’s to consider, but those are the ones I have any experience with. I personally use ZFS on Truenas with a lot of help from this YouTube channel. https://youtube.com/@lawrencesystems?si=O1Z4BuEjogjdsslF
What my setup will soon be for hardware: Gen 2 AMD epic 16 core CPU, Supermicro motherboard with lots of pcie slots, 128g ram, Intel arc a40 GPU, HBA card attached to a super micro disk shelf
Software: Proxmox for host is, Truenas Scale (just NAS) in VM with HBA card passed into VM, Plex in VM with Intel GPU passed in, 3 VMs for docker swarm (headless Debian)
Other thoughts: Cloud flare will only be helpful for things you want exposed to the internet. If you do that make sure you have a reverse proxy. This is how I expose services for non-tech family.
VPN will be more secure, but can also be more of a pain. I generally only do that for things only I need or only techy savvy people will use.