1) The faq is actually in the same forum that you've posted your question in. Look at the top of the list of topics.
2) I've personally never played with a brand new Opus, so I'm not sure what it comes with in the box. However, it is what you want, and there's enough people here to help you figure out what to do with it.
Just buy the damn opus
3&4) Cross off the power switch. The opus will turn the carputer on for you when you start the motor. You mentioned you didn't want a touch screen, but you're going to need something to control your setup... Go ahead and put the touchscreen back on your list.
5) Sound OK to me... whatcha going to put all this stuff into? Regular ATX case?