Power consumption is the main issue. If it’s an old, power hungry desktop and you live somewhere with expensive electricity, it can be quite costly to run. If you have an energy efficient desktop or have cheap power then it will be fine. Just make sure it has a good quality power supply if it’s going to run 24/7.
The hard drive should be connected by SATA or eSATA when making the image. Connecting over USB is just asking for more trouble when the drive is not working correctly.
I’ve gotten both of my thinkpads used, so none of that money went to Lenovo or Microsoft. The laptops that come with Linux are expensive and are rarely available used.
I still get over 12 hours of web browsing or video playback with the backlight around 30% on mine even though my internal battery is down to 60% capacity and my external is around 90%. Standby drains about 10% overnight. I am running Linux Mint on mine and I set up TLP. Undervolting can increase the runtime quite a bit, but I haven’t bothered with that yet.
MELF stands for Metal Electrode Leadless Face although anyone who has had the pleasure of working with them will tell you it stands for Most End up Lying on the Floor.
The T480 and T580 are some of the last ones they made with swapable batteries. Everything works out of the box in Linux except the fingerprint scanner which needs some additional configuration.
I have a T480 with an integrated GPU and the largest battery. It runs for a long time on a charge and there are lots of spare parts available.
It could be resized too. 5120x1440 is way too big for a website banner. There’s no reason to go more than double the size it will actually be displayed at. That would bring it down to a couple hundred KB.
You’re probably not going to find a tablet with modular RAM, but 4GB will barely run a web browser these days. You will be using swap a lot and that will put a lot of wear on the non replacable SSD.
You can run multiple X servers for a graphical multiseat setup. It’s a lot of work to set it up and most of the information about it is out of date though.
I’ve never seen any of my ~/.cache directories get more than a few GB either and I never bother to clean them.
I am curious what OP was doing that used that much space though. That’s certainly not typical.
You could have a cronjob run something like find /home/user/.cache -type f -atime +30 -delete, which would find files that haven’t been accessed in the last 30 days and delete them. Make sure your home partition is not mounted with the noatime option though.