Correct me if i'm wrong. Default win software opens two serial ports for the bluetooth device, one IN and one OUT. The only problem why I can't use the Arduino serial monitor is because it can monitor only one serial port. But if i had software which can read two ports simultaneously, this would be no problem. Am I right?
I tried that too with the default windows bluetooth driver. I opened two instances of my PC terminal program (brey terminal) opened one at one of the comm ports the other to the other comm port, wired a loop back wire between the rec and send pins of the BT modem, but nothing worked, however I suspect the the brey terminal disconnects one instance's comm port when you select the other instance, so maybe not a valid test.
As I said I could get nowhere until I installed the toshiba BT driver stack. With the toshiba it creates a lot of comm ports for various BT applications that it also installs, but the comm40 port it creates seems to work for any application including the Arduino IDE serial monitor.
Lefty