Yes, you can also use the device without music to use only the active noise cancellation (ANC).
Unfortunately, we cannot make a definitive statement regarding the noise, as we do not have any empirical data. However, the question remains in the Community in case anyone can help.
The 2nd Gen support the Bluetooth audio codec aptX Lossless via Snapdragon Sound, provided the paired device uses Qualcomm 8 Gen 3 or newer. This means aptX Lossless is available, but only with compatible devices, not generally for all Bluetooth connections. They also support aptX Adaptive, SBC and AAC.