It doesn’t have to be on all the time. When you need to verify that you’ve received a transaction you can just turn it on, open knots or core and they’ll grab the blocks you missed since going off line. It doesn’t take too long to catch up on a few weeks or months. If you wanted to run a lightning node then you’ll need to be online but let’s be real—even the big brain hacker types on here who run their own lightning nodes are constantly running into issues with their node. It’s a pain to manage and maintain and loads of services exist that do a great job for very little money to maintain one for you.
To your second question. It’s relatively easy to set up an old think pad and they’re everywhere on eBay. I have 2 intel i7 16gb ones that I got off eBay. Plug in a new hard drive, a usb stick with an os and follow the installer prompts and you’re good to go.
