What country do you want to operate this in? I don’t see any approvals information in the manual.
As their is a protocol involved then it looks like their is not a constant sustainable data rate it looks like it gets interrupted. This will result in noise in the audio signal, unless you are very clever with the buffering. In short it is not as simple as you think.
Bluetooth is a Radio Frequency protocol. And if you had any idea the amount of money and time spent getting that to not be complete rubbish for audio, you would understand the challenge you are asking about.
Arduinos are not a good option if you want to handle audio, looking into a pair of Raspberry Pi's will better suit your needs. They can handle the Bluetooth A2DP protocol so you don't have to invent a digital audio compression codec for yourself.
I am making an assumption that the 'audio' you want is more than simple beeps or buzzes, but you didn't give useful information in that regard.
Two way communications is a whole other ball game. You can only have one transmitter sending at one time, so their must be a way of switching between the two data paths. You have what is known as simplex communications not duplex.
The normal cell phone gives the illusion of duplex communications by clever switching between the two modes.
Several hundreds of meters apart is not going to happen with Bluetooth.