Based upon the information given, your symptoms are not on a cardiac basis, unless you are having some type of arrhythmia. The rapid breathing and light-headedness on awakening is most suggestive of hyperventilation syndrome, especially since it is not evident during exercise.
You need an objective evaluation.
Spirometry and probably an exercise study would rule out arrhythmias, hyperventilation and asthma, despite the apparent absence of exercise-induced bronchospasm (EIB).
The breathing symptoms could well be related to the Buspar. You and your doctor might have to put this to the test.
If the night sweats are real, and "drenching", and are of recent origin, they could be indicative of tuberculosis (TB) or other pulmonary infection. While night sweats are typical of TB, TB does not cause most night sweats. They are more likely functional, possibly related to anxiety, but a chest X-ray should be done and a record of temperatures, especially during the night, kept.