Hmm, this is the soon-to-be art student, yes?
Calm yourself, Grasshopper. You are about to be awash in information and other things, and somewhere in it you may find the answers you seek, or you may find something you can form into your own satisfactory answer.
I can't give you my own answers to all your questions now, but relax in the knowledge that everyone has their own answers, and there isn't one truth to any of it. It's all gray area, with little shining highlights of absolutes around the edges.
As for 'artistic vision', this merely refers to the ideas that artists try to convey in their work. If you have a strong vision and the skills to represent it, then you will probably be able to create some fulfilling work.
Just remember: Picasso was kicked out of the Louvre permanently because he was going into the museum with paints to touch up his own works while they were on display. I think he's the one who said "Paintings are never finished, they are merely abandoned."
In seeking your answers, simply keep asking yourself, 'what do I want to do?' It's okay if you change your mind three or four dozen times, too. Just keep going.
P.S. I used to feel like you. Now I long for that time again!
'don't believe everything you think.'