Um, YEAH.
Steven, diplomacy is precisely by its nature an exercise in moral equivalence. We did not send Colin Powell up to Afghanistan on 9/12 to have a sitdown with bin Laden.
Ummmm. No. Diplomacy is the realisation that different entities have different priorities and that those priorities don't always match up with our own and that you don't just start war with every entity you have a disagreement with. We have diplomatic relations with Great Britain for example. Sometimes the US and the UK disagree on things though. What do we do? Bomb London? Well, in the past we did fight with the Brits over territorial disputes (War of 1812 and they did burn the White House). But this is not how we carry on with each other today and I think only a fool wants war when there is another way to resolve a dispute. War should be a last resort.
Diplomacy is not a policy- it is a way of treating with each other. The Golden Rule, for example, is diplomacy carried on at the individual level. At the end of the day, getting along is almost always preferable to not getting along.