3. Autoconfig doesn't guarantee a machine will have the same IP while DHCP will
sure it does. autoconf is based on the mac address and the subnet as advertised by the router (rtadvd on openbsd) -- the address will always be the same. you really are just making your life difficult.
Trucks and cars are even easier to load with explosives and pilot into a target, as they have been. Remember Lebanon? The first World Trade Center Bombing? Oklahoma City?
yep. cars are in the same class in that respect as planes. have you seen government buildings, recently? they've all implemented security measures against cars. ditto for marine barracks. it's practical in that case to defend the targets. i guess you could dispense with all the security around airports and just shoot down the planes. but someone probably wouldn't like that.