He certainly doesn't lip service the fifth commandment.

To be completly accurate, the fifth commandment is "Do Not Murder", not "Do Not Kill". As you say, sometimes decisions have to be made that result in death that would not be considered murder. However,

His smirking 'saddle-up' attitude when it comes to matters of death (Saddam's sons, the death penalty etc) does not exaclty demonstrate any reverence for that commandment.

is a really good point. In fact, I have been dissapointed with a lot of Christian's reactions to death as far as Saddam and his sons are concerned. It is completly valid to rejoice that a threat has been dealt with and victory achived, but we have not limited our celebrations to this alone. I heard someone I respect exclaim with glee "hang him high!" with regards to Saddam, and I just feel this isn't right. Not that the death penality shouldn't be invoked, but it isn't something we should take pleasure in.

So yes, that is a very valid criticism of Bush, and many Christians in general actually. Which only illustrates that we make mistakes and are in need of grace just like anyone else. However, the stakes are much higher when you are the President.