There are CI tools like Prow and Tide which make it possible to use squash by default while still giving control to developers who want to use a different merge strategy.
Start with a language that is popular in your domain of interest. If that's systems, learn C. If it's data science, learn Python or Julia. If it's web, learn Javascript.
This was my first hold up. I think the correct answer is to print the test onto a substrate that can be molded into a sphere. Then you can draw a geodesic around the number.
What DE or WM (and distro if relevant) do you use for your actual, professional work?
I use both a MacBook and a Linux desktop running NixOS + Sway. I use the tmux + Helix editor on both. It's not uncommon that I will use my MacBook as a thin client for coding over SSH on my desktop. But the MacBook is actually quite snappy for building Rust code.
Do you need to balance stability vs. customisability?
While NixOS can be bleeding edge, I also quickly notice breaking issues and I can easily revert to a previous working boot image (there is a history of boot images saved in the boot loader).
How much time do you find reasonable to put into maintaining/developing your setup?
I think it's reasonable to spend a few days just getting to a working state, assuming you are starting from scratch. The long tail of maintenance should thin out quickly to the point where you are never really touching your config anymore.
Did distro choice (or lack thereof) impact your choices for DE/WM?
No.
Do you feel like your code editor, language stack, or job profile has an impact on the choices?
Not really. One time I did need to get a Windows VM running just to test out one of our Windows builds. A bit painful, but now that it's done, I don't really have to worry about it anymore.
If you can achieve the desired UX on web, I see few reasons to build a native app. But of course it can be hard to work with web technology sometimes; Javascript and WASM can't do everything and they aren't the best developer experience compared to more moderns languages.
Even for offline usage, there is increasing support for progressive web apps. For example, I don't even need to be connected to the internet to use Exaclidraw after I've loaded the app once and installed it as a PWA.
Then there are times when you simply need access to native platform APIs. SQLite is a a very important technology that isn't easily used from a web app. Most of the powerful APIs you get from an OS like the file system or graphics APIs are extremely watered down for the web.
There are CI tools like Prow and Tide which make it possible to use squash by default while still giving control to developers who want to use a different merge strategy.