Protok

First off Hi to everyone you have a great site here
Second i seem to keep finding stuff that contradicts itself so i would like to ask a few questions and maybe get some answers from everyone and maybe even opinions.
1st) Would i be able to intergrate my headunit into the CarPC and keep it an active part of the car?
2nd) Is it possible for me to get rid of the heating controls and control them through the CarPC?
3rd) Would installing a second battery to the car help with keeping the car from dieing?
4th) Is there a possible way of using a PDA to control the car and the CarPC

thanks in advance
red