1) Answer is: WO3 + 3H2 → W + 3H2O.
Reduction reaction: W⁺⁶ + 6e⁻ → W⁰.
Oxidation reaction: H₂ → 2H⁺¹ + 2e⁻ / ×3; 3H₂ → 6H⁺¹ + 6e⁻.
Wolfram change oxidation number from +6 to 0 (reduction) and hydrogen change oxidation number from 0 to 01 (oxidation).
In other examples, elements do not change their oxidation numbers.
2) Answer is: It increases the average kinetic energy and there are more collision per minute.
The collision theory states that a certain fraction of the collisions (successful collisions) cause significant chemical change.
The successful collisions must have enough energy (activation energy).
Chemical bonds are broken and new bonds are formed.
Particles are in constant, random motion and possess kinetic energy, molecules faster and have more collisions.