How would the kinetic energy of the ball in questions 4 charge if its mass were doubled if its speed were doubled

Doubling the mass doubles the energy, while doubling the velocity quadruples it. Your question is basically about order of operations; the exponent only applies to the variable it's immediately on. As you note, you'd have to put parentheses to make it cover the
m as well. We say that energy is linear in mass, but quadratic in velocity.