1.The latest dual cores would work great. You want to try to target the low end of the latest stuff as to save power.
2. Probably just USB support touch screens are a lot like mice.
3. The DSATX Should have no problem in most setups. Just try to keep power in mind when choosing the CPU. The more heat sinks and fans the more power. When choosing a video card, chose one of the lower end ones that don't require active cooling. Graphics these days are taking more power than the CPUs..
4. I can't really help you here..