Yes, it sure can. The cocoa beans that are used to make chocolate have caffeine in them naturally. Not to mention, most chocolate confections have sugar in it as well. The combination of the sugar and the caffeine could certainly keep you awake, especially if you eat a significant amount and are not used to taking in caffeine.
No, sugar and caffeine are two separate entities. Caffeine can keep you awake and make you hyper. Sugar is one of the fast body fuels but in excess it can add to your weight. A sugar free item uses a replacement for the "sugars". (Fructose is a common sugar.) A caffeine free item has no caffeine in it.
That is a question with many variables, such as how strong the coffee is, how much you drink of it, how long you have already been awake/when you last slept, how much energy you have already used that day, your height and weight and a few other variables... There is no standard time that coffee/caffeine keeps you awake.
Yes, tea can keep you awake but depending on what type of tea you drink depends on how much caffeine you intake resulting in how long you stay awake. Below is a chart giving examples of caffeine in your average 8oz cup of tea compared to your average 8oz cup of coffee Black- 4-5 cups of black tea would give you the same amount of caffeine as the same cup of coffee White- very little…
No. Caffeine does nothing to help a person be aware of how intoxicated he or she is. At most, it will keep them awake when they would otherwise pass out from alcohol intoxication. In that respect, it might make them LESS aware of how intoxicated they are by giving them a distorted perception of being less drunk just because they are a bit more alert.