I have worked with case managers and case workers for over 20 years. For the purpose of developing a character, I would specify if they are a case worker (typically high school education in my state) or a case manager (either a nurse or a licensed social worker depending). Many case managers specialize (discharge planning from a hospital or work with a specific disease state while others don’t).
The biggest thing I have noticed over the years, is that case managers (and case workers) don’t make much money. As such, you typically attract folks new to their field (who are ok with the entry level wage). Many have the best intentions and very little life experience. For example, I have seen a 25 year old trying to tell a 50 year old former stock broker about how to do his budget (it didn’t go over well). In many instances, the case manager/worker is charged with assisting people with some basic aspects of activities of daily living. Some of this you can learn from a book of theoretical models, but much of it is gleaned from living a lot of days.
If your character is a social worker, there is the National Association of Social Workers (NASW) booklet on ethics. Therein are some fundamental principles of the profession. You could have a very interesting element in the story of a young social worker in conflict with an element of social work ethics. One I have seen play out many times is in the area of dual relationships (e.g., I am the social worker and you are my client, but now this is bleeding over into a friendship and the lines are starting to blur).
Social workers are typically divided into clinical (those who see clients) and administrative (those who supervise other case managers or programs). They have different types of training depending on the specialty.