"When will he have graduated?"
Translation:När kommer han att ha tagit studenten?
We'd use this one when speculating about the future. We're discussing this young man's future and when we see his graduating as something that will be completed at a certain point in the future, this is how to say it. Of course we rarely need to use this construction, so your sentence is much more useful, but it doesn't mean the same thing. In English, it would be When will he graduate?, again a very useful sentence, but not the same one we're teaching here.
To be able to call oneself "student" in Sweden, one formerly needed to pass final exams of late secondary school (Swedish gymnasium). If you passed, you got studentexamen, and hence the expression "ta studenten".
Nowadays, there is no longer a final exam for gymnasiet, but the expression lives on to mean having gone through gymnasiet.
Yes, from late secondary, comparable to high school. You normally finish it during the year you turn 19.
For graduating from college and university, you'll get a kandidatexamen (Bachelor's degree) for a 3-year education, Masterexamen (Master's degree) for a 5-year education and a PhD is en doktorsexamen.
So it is more like "become a student" instead of "take the student", isn't it? Maybe it's short for "take the student exams" originally?
I also have difficulty understanding "ta examen" meaning graduate. I mean you could take the exams and fail... Only if you pass the exams you graduate. Or does "ta examen" actually mean pass the exams in Swedish?
The meaning of examen has shifted in Swedish from its original "test of knowledge" to the modern "succesful test of knowledge". So it shouldn't be thought of as an exam today, but as of a degree. Hence, it's something you can take.
The expression ta studenten comes from the longer ta studentexamen, using this modern meaning. To do this today, you need to fulfill a set of criteria but it's not dependent on passing a single exam or small number of exams.