Here is the Occupational Outlook Handbook entry for Librarians and Library Media Specialists, which has information on qualifications, typical salary, growth, etc.
Here is the American Library Association page on Library Specialties, which desrcibes the different types of library careers there are. Librarianship is changing rapidly. Here are some things to consider:
Regarding education:
- Apply to graduate schools with ALA accredited library/information science programs.
- Do not worry about what your undergrad major is. Librarians come from all educational backgrounds.
- If you want to be an academic librarian in one of the larger universities, consider getting a second masters degree. If you want to be a subject specialist, get one in that subject area.