Yamaha - 5.1-Channel 4K Home Theater Speaker System with Powered Subwoofer and Bluetooth Streaming - Black

The rear speakers are hard wired and the speaker wire to hook the rear speakers to the unit is included with the unit. The Bluetooth allows you to connect a Bluetooth device to the receiver so you can stream audio (only audio no video) to the receiver. A perfect example would be your phone. I use the Bluetooth to play music from my phone to the receiver. You just switch the input on the receiver to Bluetooth and do a scan on whichever device you want to connect to the receiver and it automatically pairs with the receiver.

I think the subwoofer has plenty of bass and have cranked it only to half before and had it vibrating our floors. There is a individual volume control knob on the back of the subwoofer which will allow you to turn it up. There is also an individual subwoofer bass level control in the receiver and the receiver has a button on the remote you can press for extra bass. The subwoofer included with the receiver is a "powered" subwoofer so it has to be hooked up to it's own power outlet. The powered subwoofers perform better since they don't have to draw power/voltage from the receiver. You can use a different sub with the unit and most subs will work. If you buy a sub, go with one that is a powered sub and not a passive one.

No, they are all hardwired and must be connected to the back of the receiver using the included speaker wire. You would have to buy a rear speaker wireless kit if you wanted the rear speakers to be wireless.

4 and 1

Yes