Studs are on the bottom of the cleats. Or they are the really good soccer players that are studs. :)

no they have not been or atleast i havent heard yet.

For grip. When boots were first worn they were working boots and the studs were flat. Protruding studs made of wood were created and these were nailed into the shoe sole. These later were made of rubber moulding and later alluminium screw in versions. Studs were and are used to provide grip in grass and muddy conditions thus allowing plays greater maneuverability

wheel studs? head studs?

Character studs allows you to get studs every time you defeat an enemy, such as a policeman or a joker henchman.