The headphone jack on the 8900 is 3.5mm 4 pin. Can a standard 3.5mm 3 pin stereo headphone jack be used for music only w/o causing harm to the device or is an adapter recommended?

Sure can! You will need to remove the headset to make or take a call though.

I do use a Bose In ear headphones on my device whenever I want to listen to music.