Can i plug the USB cable into the TV

As you indicated, the stick shuts off when the TV shuts off. To me, that isn't a problem because I don't mind the stick getting a chance to cool down when not in use. I had the original purple streaming sticks some years ago, and they ran quite hot all the time, and my friends who kept theirs plugged to a power adapter - stayed on all the time and their sticks eventually died. My purple sticks never suffered too much heat because they got to cool down every day. The current 4K stick I've upgraded to a lot cooler, but still I let it cool down overnight; it starts up so much faster than the old sticks that it doesn't bother me to wait a couple seconds. In terms of updates, the OS will check for updates at various times of the day, so it isn't only overnight.