False. there are many more indicators such as height for age, lip color, and hair loss.
The blood vessels dilate to increase the "blood traffic" through the lungs to carry more oxygen to the muscle. The lungs work harder (faster respiratory rate) to increase the rate of oxygen/carbon dioxide exchange in the lungs.
Most people start to face new issues at the ages of 11-13 some may gain this at older ages, but it typically starts around that time, some causes of this are: Puberty;School; Problems at home; etc.
Number 2 unless you are 18 years old or older and number 3 yes marijuana is legal in some states