User blog comment:EliteRacing343/Black Ops II Questions/@comment-1784397-20130420225408

You do not need to prestige, it's player choice. Combat Training with A.I can be played at any level iirc. The Extra Slots pack lets you make more custom classes, but they retain the Pick 10 system. You must buy Uprising to get Mob of the Dead. That last one, I do not know.