1. Toluene is organic solvent so it will dissolve the acetone more readily than water, and it's immiscible with water. So you can use separatory funnel to extract the acetone from water after shaking it.
2. Acetone is relatively polar so it will dissolve in water too, you should know the partition coefficient of acetone to know where it dissolve to a large extent. so in this done by shaking the mixture of toluene and acetone with water in separatory funnel.
3. I don't know
4. It represents the purity of the compound, that is similar to the melting points, such that the melting point of a pure compound differs from the melting point with impurities.
I hope I help you in something
Mohammad Momer