no
Its IS226 for structural steel & IS2062 for fusion weldable structural steel.
Depends on the type of stainless you are referring to. Martensitic stainless steels could be made harder then mild.
By thick control.
Per the attached related link, the density (hence weight) of stainless is slightly more than the mild carbon steel. Using about 8.03/7.84 ratio of density, for the same volume of material the...