I would recommend searching and reading... you'll find most of those answers allready in stickys and stuff. People get anoyed seeing the same questions over and over again, and I can understand why.
My thoughts are that you need more ram, and alot more planning. What are you going to do with the computer? Where are you going to mount it... do you want to deal with plugging in and unplugging the computer everytime (cause it will drain your battery in one nights time if you leave it plugged in... especially an inverter.) The automatic shutdown controllers are typically for pc's with power supplies in them... not laptops with external ac adapters and built in logic.
Laptops allready have so many valuable shutdown abilities built into them... a battery, a lid switch and so on, you just need to rip it apart and solder wires onto the points to use these items.
Good luck... its not an easy task... once you get it installed the fun begins of getting it to work right.
Oh, and touch screen use usb.