You didn't get any answers as everything you have asked has been answered before.
There are several different PDA holders for placing the PDA at stereo height, the higher
any aerial is the better and bluetooth is convenient for this, you can play the output
through the stereo but there is no point a PDA speaker is plenty loud enough. You can
search this forum for ideas/pictures and also check out
www.newministuff.com
and
www.globalpositioningsystems.co.uk for ideas/pics/prices.