"Who does #2 work for?" The answer, really, is quite simple: the Kingpin/Queenpin (Executive Director). Too bad Austin Powers never figured that one out!
As the orchestra manager, you will need to have superb organizational skills and a knack for time management. Your responsibilities will include getting to rehearsals early to set up equipment, taking attendance, managing the executive staff, fulfilling the Music Director's requests, and helping to set up schedules, among other things. But, while juggling these many tasks, you must still be able to project warmth and friendliness. Most importantly, you should be able to remain calm in potentially-stressful situations. You are truly the handyman of the MSYO.