could some one please help me with following details for my college project.

(1)for sheet metal i need the following datas:
Calculations for bending allownce,bend radius,bend angle,blanking,etc.,
Formulaes for bending allownce,bend radius,bend angle,blanking,etc.,,
international Symbols for bending allownce,bend radius,bend angle,blanking,etc.,,

(2)Details about welding symbols what are the symbols available & where it is used ?

(3)Details about surface finish symbols what are the symbols available & where it is used ?

(4) how the differential works in automobile ?

If possible please provide me with the web links.