All Legion Officers are listed in the
Legion Command Staff and Administration page.
All unit leaders are listed along with their current staff under their units within the
501st Legion Master List of Units.
Alternatively, you should be able to find your Command Staff listed on each unit's website/forums (which can also be found by clicking the links under the unit within the Master List).
The Master List also shows a complete list of all active Garrisons, Outposts, Squads, and Detachments, complete with contact information and roster lists for each unit.