How many days can a human go with only eating a little bit of food? for example for breakfast a banana, for lunch a small bowl of salad, and for dinner half a sandwich.

This is first hand knowledge, top-level athletes, successful business people and achievers in all fields all  set goals. setting  goals  gives you long-term vision and short-term motivation . it focuses your acquisition of knowledge, and you to organize your time and your resources so that you can make the very most of your life.

Frequency of exercise, intensity, time allotted, and type of exercise 

Yes but it depends where you want to go