Go to the Student Activities Office and ask them what they require for student organizations. You will probably need a constitution, bylaws, faculty advisor(s), and officers. They may be able to give you examples of the constitution and bylaws or the officers of another organization may be willing to give you copies of theirs. Faculty advisors usually aren’t too hard to get, as long as you ask faculty members who don’t have too many other committments already. When profs apply for tenure, service to the university community is one of the criteria that they need to meet. So, the easiest way to find a faculty advisor is to talk to tenure-track profs who need you as much as you need them.

You need to speak to your principal and ask. It is usually stated in some kind of Constitution. Otherwise, it is up to the discretion of the principal.