Good questions.
1. Depends on the structure of the organization in question. Could be a Board of Directors, could be a Board of Regents, etc. Ideally all organizations would have written guidelines detailing impermissible behavior that would make this process simpler. That said, in my experience talking with people about the issues they've experienced in a workplace, these processes are often structured to protect management or the company, and people don't complain because they don't think they will be given a fair shake and that they will then be ostracized and held back in their career.
2. See the answer above. This is why it's important to have written guidelines. In talking to people who have been treated unfairly in the workplace, "gray area" is what has often let people get away with abusive behavior. Therefore gray areas should be avoided.
3. Everyone deserves due process and to have their side of the story told.