A:AnswerIt does have a mic and it works very well for my zoom calls. In regards to the OS, logitech website says windows 7 and up. So you should be fine.
A:AnswerI sometimes use a headset with a microphone when using the camera. When I plug it into my PC, it takes over the microphone function and turns off the microphone in the camera.
A:AnswerProbably you can attach it permanently using double sided glue tape. But you need to extend USB cable (there are limits on length) and it does need additional light. I would rather search for cheap wifi security camera you will need only provide power.