Zinc is known to possibly help improve acne, Vitamin C will fight free radicals which can age your skin, and Vitamin E helps elasticity and can aid in fading acne scars (though some say it breaks them out, starting the pimple and scar cycle all over again).

Using Vitamin C & E topically rather than ingesting them would be more benefical if you're looking for skin benefits.

This kind of question doesn't make much sense to me. If you have a shitty diet, a Vitamin C supplement won't make much of a difference. In my personal experience, and in reading the journeys of others on this board, the road to smooth skin comes from a consistent, nutritionally dense diet free of junk food and intolerances.

What does your diet look like? Are you getting most of your vitamins and minerals from fresh, whole foods?