Hmm, it’s been ages since I’ve changed anything, I bought the most recent one a few years ago. I thought I just used Piper, unless I put G Hub on a VM and did it that way. My custom DPI settings are saved to onboard memory, so I haven’t had to change them since initial purchase. I’ll try to remember to check on that sometime I get the chance.
I usually recommend pcpartpicker.com to pick out the parts themselves. I’ve used it to build a few computers, and it makes it very easy to decide what you want.
As for Linux compatibility, many things should work right out of the box. I would agree with the other person that mentioned the motherboard being the main thing to watch for. Other than that, Nvidia GPUs would be the only thing I would avoid, just because they don’t have drivers directly in the Linux kernel yet. You can install them yourself or use a distro that has them already built in, but it’s just one more thing you might need to work through.