A:
Unfortunately the way PS4 itself is set up, if you want to use the mic, you have to hard wire connect to the controller. But if you only want to use it as headphones (without mic) then YES you can disconnect the wire. I use it like that from time to time.
As for the second part, I have hard connected it to my TV (Samsung) and used it as a headset. You can use the chat volume controller, to control TV volume. The wire is short, so you need to pair it with another longer cord.