Install the attached CAB file to add A2DP support to the Prophet, I know you don't have one yet but the file's there for you and anyone else who's interested. Ignore the "Tornado" part, it works fine with the prophet.
Although the Prophet's processor is a bit on the wimpy side, it can cope with encoding audio for Bluetooth Stereo, but you will find that trying to write a text/e-mail at the same time is a bit frustrating though. This can be solved by overclocking, which I do only when listening to music. The Batterystatus Today Plugin by Chi Tai Dang (Website)
is a very good utility and allows you to change your prophet, or any other WM5 OMAP 850 device's processor speed with a single tap. Of course, you use this at your own risk, but I've never had any problems overclocking to 234Mhz.
Install the cab file and do a soft reset, pair up with your BT headphones and then in your "Devices" menu hold down on your Stereo device and select "Set as Wireless Stereo". If this option is not there then install again. This happened for me a couple of times, not sure why but it's there eventually. You should also see "Set as Hands free" if your BT headphones work as a bluetooth headset too. I can confirm that this hack works fine for both profiles on headphones such as the Motorola HT 820, provided the player you are using knows to pause playing when a call comes in.
Hope this helps, if you need any more info don't hesitate to PM.