StarDestroyer.Net BBS

OK we know Vader(pre-suit) will lead the 501st clontrooper Legion to kill the Jedi in the Temple (in ROTS) and this Legion will later be renamed the 501st Stromtrooper legion aka the "Vader's Fist".

Now my qestion is, was this Legion under Anakin's command before ROTS or was it gives to him for the Temple Purge mission?

EDIT:Also what does a Clone-/Stromtrooper Legion consist of?

A ST-Legion is the same as a ST-division and contains 9,700 men (at least during the ImperialEra).