Hey nice question!
Ok for the first one:
It's H2SO3, not H2SO4 (maybe you got it wrong because you read this wrong?)
If you mean H2SO3, the oxidation state of S in H2SO3:
-We know the oxidation state of H2SO3 is 0 because its not charged
-We know the oxidation state of H is +1
-We know the oxidation state of O is -2
-Therefore with some maths: 2(1) + [Oxidation state of S] + 3(-2) = 0
-[Oxidation state of S] = 4. It's oxidation state does not change in B, it's +4 in HSO3 and +4 in SO2
Second one:
Ea refers to the activation energy of a reaction, not what you might think as the rate of reaction.
The activation energy of a reaction is something that is specific to a reaction, and changing the conditions won't change it. (Even adding a catalyst, the catalyst would just provide an alternative pathway which this pathway would have a lower Ea - still the original reaction has the same Ea)
Hope I helped a bit!