Mathematica Module versus With or Block - Guideline, rule of thumb for usage?

Question

Leonid wrote in chapter iv of his book : "... Module, Block and With. These constructs are explained in detail in Mathematica Book and Mathematica Help, so I will say just

Answer 1

I'd like to mention the official documentation on the difference between Block and Module is available at http://reference.wolfram.com/mathematica/tutorial/BlocksComparedWithModules.html.