This first table (from page 13) lists the field and staff officers:
Colonel: Rufus P Tapley (later Mark Wentworth)
Lieut-Col: Mark F Wentworth (later James Stone)
Major: James M Stone (later John D Hill)
Adjutant: Edward M Rand
Quarter-Master: Lewis O'Brien
Surgeon: John E L Kimball
Ass't Surgeons: Freeman Hall, Charles M Cross (app't in Feb '63)
Chaplain: Otis F Russell (position not filled until Jan 1863)
Sgt-Major: Calvin L Hayes
Qr-Master Sgt: John Hall (later Horace H Burbank)
Com. Sergt: William H Tapley (later Cyrus G Marr)
Hosp Steward: Ivory M Hodsdon
The "servants" were enlisted men pulled out of the companies, and can be seen listed in the monthly reports under the "extra or daily duty" section. They served as cooks, hostlers (horse caretakers), and clerks for the officers.
This second table (pg 14) shows the structure on a company level.