What can I do to reduce sweating when exercising?

Antiperspirants. Exercise regularly--reducing body fat reduces sweating. Apply antiperspirants after showering. Wear comfortable loose-fitting cotton or absorbent clothing that wicks sweat and is breathable. Avoid tight clothes especially in hot humid weather.
Normal. Sweating is the body's way of cooling down when the internal body temperature goes up.
Depends. Depends on how humid it is, how hard you work, your level of conditioning, how bulky you are, and various factors inborn in that individual. Don't worry about it.