A junior high school chemistry problem

The wastewater from a factory only contains magnesium sulfate and a small amount of sulfuric acid. The extracurricular activity group discussed how to recover pure magnesium sulfate solid from it. They have designed two different schemes, please participate in the discussion:

(1) Scheme 1: Magnesium powder is selected as the reagent.

Magnesium powder is added to the wastewater one by one. When it is observed (no bubbles are released), the amount of magnesium powder added is sufficient. The chemical equation of this process is: (magnesium+sulfuric acid = magnesium sulfate+hydrogen rising).

The next operation methods are (filtration) and (evaporation) in turn.

(2) Scheme 2: sodium hydroxide solution is selected as the reagent;

Dropwise adding sodium hydroxide solution into the wastewater, and stopping dropwise adding the sodium hydroxide solution when precipitation occurs.

The chemical reaction equation at this time is: (2 sodium hydroxide+sulfuric acid = sodium sulfate +2 water).

In order to obtain pure magnesium sulfate solution, the following experimental operations are needed: _ evaporation, hot filtration, cooling, filtration and evaporation _ _ _ _ _ _ (please briefly describe the operation process).

..... to obtain magnesium sulfate solid.

(3) Comparing the two schemes, assuming that there is no loss in the experiment, whether the final magnesium sulfate solid mass is the same _ _ _ _ _ The reason is that the first one added magnesium powder, the second one neutralized sulfuric acid, and magnesium sulfate was missing _ _ _ _ _ _ _.

(4) Please continue to explore and design new schemes (the reagents used must be different from magnesium powder and sodium hydroxide):

The reagents you choose are _ _ _ magnesium oxide and magnesium hydroxide (chemical formula is not written) _ _ _ _ _ _ (chemical formula is written):

The chemical equation of the reagent reaction is: _ _ _ _ magnesium oxide+sulfuric acid = magnesium sulfate +2 water _ _ _ _ _ _.