Hi @Len,
I’ve worked in IT for various associations, companies, and small businesses, and I was also an independent reseller for some time. I still manage quite a few things on the side. I’m 43 now, and I’ve been working in this field since I was 16. When something grabs my attention, I go all in and I guess you could say I’m a bit hyperactive (so much hyper) 
Currently, I’m involved with two non-profit organizations (ASBLs), one of which is focused on Repair Cafés and social initiatives. My wife has taken over my former company and handles IT, hosting, servers, and so on in the evenings.
Regarding Secure Boot, it’s generally only found on more modern machines or in rare cases, on slightly older ones. It’s always recommended to disable it before reinstalling any operating system, including Windows. It’s considered good practice to back up your BitLocker key or encryption data via the BIOS, then disable Secure Boot before proceeding with installation. Too often, people reinstall systems in “UEFI-only” mode but the combi “Legacy/UEFY” is the best, like MBR and GPT, go MBR, which can make it very difficult or even impossible to recover or repair the system in case of failure.
Just to be clear, this is not about forcing anyone to follow a particular method, it’s simply about offering helpful advice. Everyone is free to follow or ignore these recommendations. We’ll never demand that anyone stick to a specific “cheat sheet”. The goal is to share best practices while recognizing that other methods may also work or not.
As for your comment about potential legal issues with reselling computers with Windows or macOS preinstalled. I was a bit surprised. Generally speaking, if you purchase a machine with a preinstalled OS, and the original user sells the device, everything tied to that machine is included in the sale. That’s basic commercial law, and there’s legal precedent to support it. In my experience with various organizations, if we had to worry about those kinds of legalities every time, we’d go crazy, especially with machines from the US, China, France, Germany, each with their own systems and rules.
About your plan to set up a system with 2 GB of RAM and an old hard drive that’s great. You could even use it to host tools over the local network, or create a simple intranet site with all the reference materials for others to access when you’re not around. Something like a local README.html, organized wiki-style.
As for power management, especially battery handling… Yes, it’s a topic worth exploring. But if you stick to lightweight distributions that are optimized to minimize system load, you won’t have any issues. For example, we install Debian Server on mini-PCs or Raspberry Pi units for our backup servers. Power usage is typically between 25W and 75W, and once configured, we rarely go above 14W even under full load, 4w in idle for my personnal Debian server and 9 to 15w when i use distant desktop with apps open. Even when we add KDE, GNOME, or XFCE for local or remote desktop access, there’s no real increase in power consumption.
However, for laptops, yes the battery usage is more directly managed by the OS. Windows handles this natively, and Linux does too, but some distros are more power-hungry than others. In that regard, Linux Mint, while very user-friendly, tends to be quite heavy. It usually consumes 15 to 30% more resources than lighter, more optimized alternatives built specifically for older hardware.
And no worries at all, @Len, the beauty of the internet is that it brings people together across time zones. I work both during the day and at night, so I’m sure we’ll find plenty of chances to connect in real time!