Found out that I can hear the radio on the speaker, but since its a mono speaker, just insert the headphone jack half-way instead of full. So moral of the story is : get a self-powered audio BT transmitter plugged into the headphone slot. This might save on BT power drain but of course, not FM power drain.
As an aside, I wonder (i) whether the USB cable could support SD card readers, and (ii) whether the firmware could be upgraded to read the cards (micro/SDHC etc). One of the big disadvantages in this player is no memory card slot.