The breathing rate, heart rate, and blood hormone levels of an individual would directly provide information about that individual’s

Metabolism

Metabolism describes all the chemical processes that go on continuously inside your body to keep you alive and your organs functioning normally, such as breathing, repairing cells and digesting food.

the statement is true

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.