Question

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

Answer 1

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.