It is a tricky definition. Lots of people on FR simply treat it as the same as 'enemy' which gives ammo to the likes of Chomsky.
To be clear. If they attack military targets they are NOT terrorists unless they use a civilians as part of their weapon. (e.g. attacking the pentigon is not a terrorist act, using a civilian jet full of people to attack the pentigon is.) IEDs used on military convoys are not terrorist actions.
No, but according to the Geneva Conventions if someone partaking in armed resistance fails to identify themselves as such then they are using civilians as part of their weapon.
Kind of like pornography: hard to define, but you know it when you see it.
You're right. It blows me away that 5 years into the War On Terror, most people can't even define terrorism.