I'm wondering how this would work?? if the hinges allowed the screen to fold back on itself this would be ideal but failing that could the smaller exterior screen be used?

Also I haven't been able to find any reference to where the GPS chip is located e.g. under keyboard

the chip should be on the front cover not under keyboard. base on the most of GPS device they should put it there to gain a clear signal.

well it wil be fine since the external screen is as big as n95, so u can see better and the gps is top of the external screen.