Re: interference between Bluetooth and Wi-Fi,

Yes surely there is interference between those two technologies, and several solutions has been there. See, for example, the following page:
http://www.ce-mag.com/archive/01/05/lansford.html

The Wi-Fi device on N810, STLC4560, has Bluetooth coexistence feature, but I have no idea it is enabled or not.

However, even though those solutions can enable coexistence of Blutooth and Wi-Fi, they are not perfect. Bandwidth for one of (or both of) the technologies must be shedded down, probably by time-division multiplexing. I doubt you can achieve both decent transfer rate on Wi-Fi and clear A2DP quality, though it depends on the environment.

To make the situation worse, to dismiss away the interference problem completely, all the devices may have to jointly coordinate their use of waves, which is quite unfeasible.