Ultimately up to you, but I'd go with no GUI and just use ssh (and sftp if you need to do file transfers).
When I was using Docker, it was headless because the GUI just ate up space and resources I didn't need. All your interaction will be in the shell anyway, launching your compose.yml files.
But, if dealing with a headless machine sounds like more trouble than you want to try, install the DE if your choice and breathe easy because it'll still work perfectly fine.
I think you've put more thought into how to get started than many others would! You have a pretty good plan from what it seems. My thoughts from each section below.
Hardware: I'm partial to Crucial and Kingston for storage that is affordable and dependable
OS: I'd probably spin up a Debian install if I were in your shoes and run my services using docker-compose files. It's a quick and easy to get up and running, and despite the ease, there is still the option to do a lot of customization when you want to, and that will make it easy to learn more at your own pace and leisure.
Services: For the CalDav portion, I'm really liking Radicale.
Security: PiVPN is what I'm running on my actual RPi along with PiHole, and it was a super simple setup. I connect via Wireguard from any of my other devices.
Elon made the intentional decision to NOT use LIDAR because he's a cheapskate and unwilling to take input. He is not using an even remotely reasonable approach. He chose not to use a reasonable approach on purpose.
DHS' new guidance states that "ICE field offices are not detention facilities and fall outside of the Sec. 527 requirements. ICE does not house aliens at field offices."
Ok, got it, so these are not detention facilities.
In their letter, the lawmakers take issue with this assertion. They say that ICE Deputy Field Director Bill Joyce recently confirmed that some individuals have been held at 26 Federal Plaza for multiple days.
Wait though, that's literally a detention facility...
I just don't want my NAS doing anything other than being a NAS, so I intentionally don't run extra services there, but its a matter of finding what works for you. As long as you get to the destination you're looking for, its mission accomplished
Got an old raspberry pi laying around? PiHole+PiVPN is something I run on an old 3B+ I think, so I have something dedicated running both. But otherwise, I'd probably just spin up a container on a server or cluster and I'd probably go with debian and just run the exact same PiVPN setup script I did for the pi because it was super easy.
I'm sorry, has this community somehow become some sort of curtain community? Is the delicate interplay between the colors and textures of the curtain, wallpaper, and flooring supposed to move me in some way that speaks "cat"? How dare you! Are there no standards anymore? Have we no decency amongst ourselves? Will the mods not step in to put an end to silliness like this? I did not sign up to see boring pictures of curtains with remarkably cute little paws. What is this preposterousness?
Florida, Tennessee, and Louisiana are named for working to outlaw chemtrails in the article. Articles like this should be required to list things they have already indicated exist in a small, closed set like this. I want a list of states! Or at least their abbreviations.
They're making the kayfabe for the people who live there