1. Yes, I Subscribe to ex nihilo. But just to throw a monkey wrench in there, I also subscribe to the Genesis 1:1-2 gap.
Unsure why this should pose a problem. The Godhead (Father, Son, Holy Spirit) first planned and designed what they would bring about before they brought it into actual existence. Don't you believe that God has thoughts and plans? The Bible certainly teaches this to be a fact.
The Gap Theory does nothing to answer
ex nihilo.
If I plan to build a chair I don't have a chair yet. God, after any plans, created: out of nothing, not from within Himself. There simply is no scriptural support to say that God couldn't create evil. And since there is a verse that says He did, it takes minor gymnastics to get out of it.
2. Perhaps you missed Capps' point. Satan was not created dark. As a matter of fact he was "Lucifer" which means light bearer. Capps point is, like mine, based on 1 John 1:5 in which darkness is being used synonymously for evil. When Lucifer left the truth-light, he made himself evil. He became the father of all that is evil. But this does not mean that he cannot present himself among the heavenly council in his angelic body.
Well, this wasn't in the quote that I addressed. Regardless, Satan/Lucifer is not creative; we've covered this. Satan can distort, but the building blocks for the distortion and the possible path must be set by God. God created the ABILITY for sin to exist. Lucifer took that choice. Lucifer CHOSE to act in pride when God's principles said do not be prideful; God, as Copeland says, created the evil in so much as the reaping that Lucifer got was according to his sinful choice.
You saying that, for ANY reason, Satan can go into the presence of God invalidates your interpretation of Light having no Darkness in its presence.
David told us that if he went to Hell, that God would be there. Is there no Darkness in Hell?
Satan tempted Jesus. How did he get so close to God on earth?
Jesus took upon Himself sin, yes seven being made to be sin, in the cross. This alone invalidates the interpretation you put forth.
All scripture of this type is only saying that God is good; God has no 'bad' in Him; God doesn't wield the 'bad' (sickness, disease, hurt, etc.) on His children. That's it. Not that God can't look upon it, be in the same room as it, talk about it, etc.