#1 Answer: Because Lymphatic System protects our body from different infection and it defenses our immune system.
#2 Answer: Circulatoty System circulates blood through the whole body, carry waste throughout the body fluids, and protects our body form infections.
#3 Answer: We must prevent eating oily and fatty foods, and must exercise regularly for the normal circulation of blood. Eating healthy foods such as dark-green leafy vegetables can also help to maintain healthy blood.
#4 Answer: For the circulation of body fluids and oxygen (and other body components) of our heart and lungs (and also for the whole body).
(We cannot answer your 5th question. Please make it specific and clearer. Thank you!)