Yes to all of the above.
The way to show any variable you want and calculate the variables value is detailed here:
If you are using standard scoring, meaning the score is the same for each of the 12 questions, it is calculated for you automatically, there is nothing extra for you to do. With 12 questions, each question would be worth 8.3 points, and your total would be calculated in real time as the questions are being answered.
If you want to do custom scoring, that’s fine too, you can manage the score yourself through the “set score” and “add to score” actions. If you use these actions, automatic scoring will be disabled, and you can manage the score any way you like.