Predator Drones Killing Awlaki: Right or Wrong?

Last week Anwar Al Awlaki was killed by a strike from a predator drone.  There has been a little discussion on the matter, but I feel the media has not expressed deeply enough the two main concerns this event has brought up.
The first area of concern is the morality of using drones for killing.  Dissenters argue that this is inhumane.  If a war is going to occur it ought to be man on man.  By allowing machines to do the killing for us remotely is dehumanizing the process of war.
While this seems like a weak argument, it is rather difficult to dismiss.  I could bring up a historical argument that we have been using machines to wage war since Cain struck Abel with a rock.  The only difference is that technology is more sophisticated.
However this does not negate the first argument as the dissenter could respond that even using a rock is dehumanizing.
So this is my argument.  War is itself dehumanizing.  No matter which way you slice it, when the natural rights of an individual are infringed by another the nature of humanity is deformed.  For this reason, we should be very cautious to enter war.  In the last half-century, America has entered so many wars that her populace feels war is perpetual and a given in society.  This is a travesty that the youth in the 1960s and now today have hoped to end.
The second and perhaps more immediately important concern is that President Obama ordered the killing of an American with this strike.
This is a confusing area.  After all, Awlaki was an "enemy combatant" and we have killed enemy combatants nearly every day for the last eight years.  Why should this be any different?
The first glaring issue is that Awlaki was an American citizen.  That means he is entitled to the Constitutional rights of habeas corpus, or his right to a trial.  There is plenty of evidence to suggest Awlaki was a planner in multiple acts of terror in recent years, so I am confident that he would be found guilty in a court of law.
What surprises me also is this: Awlaki could have had his citizenship revoked on the grounds of treason.  That is a constitutional power we have given our government.  So again I have to ask, why was this not done?
I truly have no answer to this and all I can offer is vapid speculation.
What my concern with this action is how it sets up a dangerous precedent.  Looking at this from a purely legal standpoint, it could be apt to describe the killing of Awlaki as a presidential assassination of an American citizen.  If we allow this to happen unquestioned my fear is that in the future a president can turn this power domestically.
Let us think of a hypothetical situation in which a man or group is strongly opposed to a policy of a future president.  The president, wanting to silence dissention to said policy, labels this group or individual as a combatant to America and has them ordered to be assassinated.  There is no trial for these people nor an attempt to arrest them.
Do you think this is right?
I don't think president Obama will ever come close to performing such an act as was presented but I fear that if the growing power of the executive branch continues to grow unchecked situations similar to this may be quite likely in the future.
Agree or disagree with me on this specific circumstance, this is my challenge: look at what our federal government is doing and always question their actions.  Our government is a government of the people.  That means the people need to take an active role in it.  I am tired of people being disillusioned to government.  If we held our elected official's feet to the fire we might find that the policies they legislate more closely match our own ideals.
We have not yet reached the point where the populace is beyond controlling the government.  We must act swiftly and with intelligence to turn our nation around and set us back on the road to success.