Can I please get a diagnosis for my friend (symptoms listed in question)?

Your friend should go to the doctors and get a physical. The dizziness, the blacking out upon standing, the dry mouth, feeling cold, difficulty breathing, and an elevated heart rate can be symptoms of anemia, B12 deficiency, or a thyroid problem. Also, anemia can cause preexisting anxiety to get much worse, so even her panic attacks could be tied to a physical cause. In any case, she really needs to talk to a doctor about everything she is going through.