Sweating is our cooling system and if you're sweating normally, it simply means your body is working well. For now, you can make your dancing a little less intense and you will probably sweat a little less. If you believe you perspire more than the average person you might want to ask a physician if it is dangerous and if there is a way to prevent it. Otherwise, just remember that when you're active your body is burning calories and that causes heat.
Perspiration keeps that heat under control.
It's a good thing. The usual recommendation is at least three times per week for thirty minutes each at a moderate level of activity, such as aerobic exercise, jogging or dancing. But you really have to decide what you hope to achieve. Three times a week for thirty minutes won't help you run a marathon or become Mr. Universe, but it should provide you with enough activity to have a positive impact on your cardiovascular system and overall health. I don't think you can beat the food pyramid when you talk about diet simply because your body requires all kinds of foods to perform at its peak.