-Provide for the health and well-being of the crew and officers
-Assist the Scientific Adviser in pharmaceutical research, biological or chemical
When it comes to your health, there is no arguing against the CMO. Take whatever is given, but the CMO will not try to poison you unless it's a part of an sl.
The CMO has exclusive command of the Nurse NPC. He also shares command of the Lab Hand NPCs with the Scientific Adviser.
The CMO, and Nurse, have access to, along with the knowledge to use them:
-Stem cells, antibiotics, and other lesser forms of medicine
-General care tools and therapies
-Defibrillator
-Extended Stay tools
-Access to the Medical Computer for files, reports, and diagnoses
The CMO possesses exclusive access to:
-Surgery, general or advanced
-Regenerative therapies
-Advanced medicine beyond stem cells
In regards to the limits of advanced medicine, there are none. If you can think of it, the Traveler has it. But be wary. Sometimes instant cures are not the way to go.