How to organize the "university-department-major-year"

Hi everyone.

I'm building a student community and is blocked by this issue: how should I organize the student's profiles according to the "university-department-major-year" logic.

In fact, I'm looking for both the logic and the technique.

I'm now using the "taxonomy" module. I want to synchronise these on a "vocabulary" with four levels. But now I find this is an impossible mission to construct an exclusive list with these four parameters since each university has so many departments, each department has so many majors and each major calls for at least 10 years... a simple calculation : 500 * 30 * 50 * 15....

But if I make the member to tag theses information, I have no way to organize them hierarchically.

Until now I haven't found a module which allows the drop list with an 'other' terms, when 'other' terms are selected, one can tag it manually.

In fact, what I need is a system to record all these scholar information of a student since he come to university. And the others could find them via these information.

Do you have any idea about that? Thanks so much!

PS : I'm fairly poor and fresh on programming.