A:AnswerYes you can. The app needs to be downloaded. The TV has google play. Its like downloading an app from an android phone. Also, the 4K screen looks great when watching videos or playing video games.
A:AnswerYes, you can plug speakers to the TV and get sound but you are unable to get sound all at the same time from the plugged speakers and from the TV.
A:AnswerNo if you plug in headset or speaker you will not get audio from the tv speakers. If you use a Bluetooth headset or a Bluetooth speaker you will get audio from both.