Is God Able to Do Evil?

Dear Dr Craig
I hope you don't mind answering a question from an atheist if it is asked in all seriousness and with the greatest respect. My question concerns God and morality. I have heard you say that God is "essentially" good, by which I assume you mean that God's goodness is a necessary part of His being and character. I have also heard you say that being omnipotent does not involve an ability for God to go against His own nature. This would seem to imply that God is not able to do evil.
So my first question is - Q1: Is God able to do evil?
If the answer is "no" it is not clear to me how God can be said to be good, as surely an important part of being good is having the ability to do evil but choosing not to. If God is not able to do evil doesn't He become a sort of moral automaton, and not worthy of praise (at least in the moral sense)?
If, on the other hand, the answer to Q1 is "yes, He can do evil but always chooses not to", this would mean that there is some "possible world" in which he does do evil (for what other meaning of the word "can" is there?). The question then becomes - Q2: How should inhabitants of those possible worlds respond to God's evil acts? Would evil become good in those worlds (a contradiction) or would God become evil (violating the necessity of His goodness)?
(I realise the above question suggests a misuse of "possible world" semantics, but I think you get my drift)
In a "one shot" question format like this it is difficult to get into a meaningful discussion, so I hope you will forgive me if I try to preempt some of your possible answers and give a brief response to those.
A1: Yes, God can do evil but there is no possible world in which He does do evil.
A1R1: It is hard to see what the word "can" even means in this context.
A2: Yes, God can do evil but there is no possible world in which He wants to do evil.
A2R1: There would still be a possible world in which He does do evil, as even human beings are expected to do things contrary to their wants.
A3: No God cannot do evil. But He is still worthy of praise simply because it is part of His essential nature to be worthy of praise.
A3R1: This means that God's goodness is an entirely different kind of goodness to that of human beings, who only become worthy of praise by virtue of the free choices they make. But how then are we to interpret the biblical notion that we are made in the image and likeness of God (which I have always taken to refer - at least in part - to our shared status as moral beings).
A3R2: This seems to make the whole notions of goodness and praiseworthiness rather meaningless as they apply to God. They become entirely detached from the meaning we normally attribute to these terms.
Thank you for taking the time to consider my question.

Click HERE to read Dr. Craig's answer