Couple of questions...would like your opinions

We had a man that was a guest at one of our Home Fellowship Meeting ask the following question?

Can a Christian that is in the military kill the enemy?
He wanted the answer to that because of the Ten Commandments "Thou shall not kill".

Any takers on this?

Also, another question he asked was this.

What happens to the person when they die, if they did not hear the gospel. How would they be judged? Are they only judged on the knowledge that they have of God?

(Should I have started another thread with this question or is it ok?)

Any takers on this?