But to the last question about the PCI killing USB my answer is no.
Six months is short and I have 10 dollar WiFi sticks that are years old. Change make and model is my advice for the next stick.
So here is the issue. I bought a Cybertron PC a few years ago. When I set it up, the WiFi would not work. Cybertron PC decided the built in PCI adapter either was defective somehow or could not receive connectivity with the antenna being on the back side up against the wall. When they offered to replace it either with a new PCI or a USB one, I took the opportunity to just buy a better USB one than they were offering. So, the problem, you ask? Well it seems as if I go through adapters like printer ink. They work fine for six months or so then eventually act up and quit working. Usually with the same MO: As I reset (disable/enable) the adapter it will appear and disappear a few times on its own. As the problem gets worse, it does this more and more and eventually just won't connect. It has done this for many adapters -- all higher end, different brands -- without fail (word choice?). The old PCI adapter has always been completely uninstalled/disabled and the antenna removed, but the hardware itself is still in there. I know they sat when you get a new adapter to completely remove the old adapter (software/driver/hardware etc). I'm wondering: could the old PCI adapter just being in there be causing issues even if it is completely disabled?