a) copper chloride + sulphuric acid --> Copper Sulphate + Hydrochloric acid
[could you use this reactants to create CuSO4 crystals?]
In water, copper(II) chloride and sulphuric acid are completely dissociated into ionic form: Cu
2+, Cl
-, H
3O
+ and SO
42-. There is no real reaction between them.
Copper sulfate is less soluble in water than copper chloride. So, if you let water partially evaporate until you reach saturation, copper sulfate will start to crystallise first
you get copper sulfate crystals.
The same is true for the other reactions you mentioned. Those are not acid-base reactions. All you do is to substitute one anion by another one depending on solubility.
As for crystals, I guess you could do it like that. But, you may as well buy pure copper sulfate and crystallise it from a saturated water solution. Your crystallisation would be cleaner.