If it's something with a CRT in it, it's probably a good idea. It won't harm you, and it probably won't damage your other computers, but it's a good way to introduce gremlins into life, or worse, other people's lives.
It probably is a good thing to replace; things will work without it, but it's not just there for show. And, if nothing else, the detonations add some excitement to life... That said, I don't know what the original value is, I'm afraid
You can still write to floppies; the issue is that the newer OS versions don’t support writing to the HFS file system, which these floppies use. The other issue you would have is no USB drive can write to 800k floppies, just 1.4 MB ones.
As for cleaning and lubrication, I have a guide on YouTube: