You post a complex question, but an important one.
you are right, sometimes dissolution and solvation are used interchangeably. In a material sense, they mean the same thing when you refer to the process of forming a solution - dissolving a solute in a solvent (salt in water) is both dissolution and solvation.
But in physical and chemical sense, they are distinctive processes. Dissolution is related to the kinetics of solution-forming process - how many mols are being dissolved per second - and it is quantitative aspect.
Solvation, as you well know is based on a molecular interaction. The goal of solvation is stabilization of solute by complexation with solvent molecules. It is a more general principle than just solution formation, because insoluble parts of molecules can also be solvated - complexed by interaction with solvent molecules.
I hope this is precise enough.
Sources:
http://en.wikipedia.org/wiki/Solvation