Is salt and water a solution after stirring and why does stirring affect the rate at which a salt dissolves in water but not the solubility of the salt in water?
2) Yes, stirring does not affect the solubility squilibrium constant. On the other hand, the solvatation rate as a kinetic quantity is of course affected by a kinetic procedure like stirring.
In electrochemistry, this is pretty important for keeping potentials as close to constant as possible: https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Supplemental_Modules_(Analytical_Chemistry)/Analytical_Sciences_Digital_Library/In_Class_Activities/Electrochemical_Methods_of_Analysis/02_Text/7%3A_Electrochemical_Analytical_Methods/7.5%3A_Voltammetric_Methods