cellular remote starter with pa- need help with coding

I'm making a remote starter for my van that will function as a second brain for my car. I am hoping to have this:

  • start the car with password
  • control after market lights through remote and buttons on dash
  • lock doors then unlock with password
  • watch battery voltage across the deep cell and starting battery independently
  • control power to pa amp which when board is called will turn on and run phone audio
  • control power to 2-way radios so when the the car is off i can turn them on by command and a button on the dash for twenty minutes also turn on with ignition
  • read a thermometer and send a message if temp drops to low
  • tell when doors open and send a message if car was not unlocked by board
  • disable ignition
  • turn on headlights for three minutes after car is unlocked and when started

i have the hardware side figured out except the voltage sensors and thermometer which are probably easy but have never done any thing with them, but as far as software the only language i know even a little of is visual basic so I'm hoping that people can help me program it even little bits and pieces can help.

Post your hardware design, lets see how you're planning to connect it all.
Or at least a pretty detailed block diagram.