No, the ACCELERATION DUE TO GRAVITY (g) is a constant regardless of mass.
F = GmM/r2
Where M = the mass of the Earth
m = the mass of the person.
Both the karate man and the gymnast would still experience the same acceleration due to gravity if they were both on mars.
No, the acceleration due to gravity is constant regardless of air resistance or other forces. It is only the resultant force that is different. The only way to change the value of g is to change the mass of the Earth.
Free Fall and Air Resistance