Carnetix was made for primarily custom PC's that connect to a system boards ATX & power headers. Since you're using a laptop this stuff is all integrated and you don't have the flexibility to "automatically turn your laptop on with the ignition" because there's no power on headers or (Front panel headers).
Your best bet is to buy a AC/DC power inverter with a regular wall plug and plug your laptop into that for power.
Sound card from your laptop probably won't be what you're expecting given the nature of MOST line-outs on a lapper. Your best bet here, is to buy a USB sound card and connect it to the laptop.