Nope, as much water as necessary to get the desired consistency. I think this is covered in one of the previous links - paints vary so no formula can be relied upon to work with the paints you have there; even your own formulas might not work in later years.1.basecoat (1 drop of water for every drop of paint
For each lighter or darker colour? Yes.*Always shrink the area in which you apply each highlight.
Yes. Depending on how dilute the paint you're using is (and which colour you're using) you may need to apply many coats, generally it won't be only three or four, more likely 5-10.3. Apply the same color over several sessions to achieve the wanted color