... we just do the calculation and divide the amount of water between water and glycerin ??
Yes. You can choose any proportion of glycerin to water.
"......is there a required temp i should wait to add my lye or just by dissolving the glycerin i add it , and after the 2 ingredients being dissolved i remove it and stay a while and add it to the oils or add it immediately??..."
I am not sure I understand your question, but I think you are asking "should I add the lye solution to the fats while the solution is hot?" The answer is yes, you can add the lye solution while it is hot.
"...why we would use a superfat if we used sodium lactate, aren't they do the same job, providing smoothness to the pates ?..."
No they are not the same. Superfat is a fat. It ensures there is no excess lye so the soap is safe to use on the skin. Superfat can also increase the mildness of the soap on the skin. Sodium lactate is a salt. It modifies the texture.
"...is the liquid soap can be considered as a body wash? and if not what is the difference ??..."
Body wash is technically a non-soap cleanser made with synthetic detergents. In the US, non-soap cleansers can not be called "soap" by law. (I know you are in Egypt.)
Liquid soap is a cleanser made by saponifying fats with an alkali. It can be called "body wash" or soap, as you wish. "Body wash" in this case is simply a fancy name, nothing more.