Does it really produce 7.1.4 surround?

It has front, rear surround and height drivers plus a subwoofer, so it can render 7.1.4-style effects. The height channels are up-firing drivers, so overhead effect depends on ceiling height and seating.

Is 840W the real output?

840W is peak power across all channels. Continuous RMS power per channel is much lower, which is normal for soundbars in this class.

Do the rear speakers need wires?

The subwoofer and rear speakers connect wirelessly to the bar, but each rear speaker still needs its own power outlet.

Which inputs does it have?

It offers HDMI, optical and coaxial digital inputs plus Bluetooth for streaming from a phone or tablet. Check the exact port list for the version you buy.

Will it decode Dolby Atmos?

It supports Dolby Atmos decoding on Atmos-equipped content over HDMI. Sources without Atmos play in standard surround.

How does it compare with a 5.1.2 bar?

It adds two more surround channels and two more height channels, which gives wider rear coverage. A well-tuned 5.1.2 bar from a major brand may still sound cleaner.