I had a brief look at the spec for your Denon.
1. It supports a CD optical connection and unless you are already using it for another device you can connect a B2 using that
Your receiver will handle the 2 channel signal and route it your speakers
2. Bluetooth output does work but not for all devices. It would depend on the headphones/speaker you are trying to connect to.
You can connect a separate Bluetooth transmitter to the B2 which can help with connectivity and also Bluetooth range.
3. For rooms out of Bluetooth range a Heos compatible speaker would be an option as long as you have a wifi network with strong enough connectivity.
John