So basically I could make one hell of a iced coffee drink. Have you tried any nibs in it? Also would some beans work better than.extract? Also would a simple syrup male the sugar dissolve better?
I have not tried nibs yet, they should be nice. I would probably add them to secondary.
If you wanted to grind your own beans that would be good. I wouldn't use whole beans for the cold brewed coffee. They won't extract very well. If you leave the coffee solids in when the alcohol is being produced the alcohol will start extracting bitter compounds from the solids. The point of doing the cold brewing is to prevent that.
A simple syrup would make it easier to mix the sugar in as the sugar crystals are already dissolved. It will also bring more water to the party, so you would be increasing the batch size a little bit and slightly diluting the coffee.
I'm thinking of adding some vanilla bean to secondary on a future batch. That should be nice.