It is determined by the number of seats available at the college. Calicut University does not conduct exams properly, and your grades will not be corrected. This means that the student who studies the best in class and the student who did not study for the exam get nearly the same grade.
The university doesn't even properly correct the papers. It's also evident in newspaper articles about the majority of students failing a university exam. Your semester exams will be held on an irregular basis. That is, if you are in the third semester, you may write for the first semester.
Furthermore, if you fail at some point in the third semester and all of the other semesters succeed, it will take years for you to pass the exam because the supplementary exam is not given frequently.
The simple answer is Yes. The marks of all the complementary subjects are included in the final percentage. The scores obtained for each subject in each individual semester are included. Apart from this, the score obtained in each course (Core/Complementary/Open) is also mentioned below the Total Score.
This information is applicable only on the Final Marksheet. As for the Degree Certificate, only the final/overall Grade obtained (of all the courses combined together) will be mentioned.