How is the CUSAT rank calculated? Does it include marks?

No, +2 marks are not included while calculating CUSAT rank. Being a student here I can say that the only thing that is taken into account while calculating the rank is your CAT exam score.

However, there is a dependency on which category you belong to, that is, your category such as general, OBC, SC, ST, etc has an impact on the rank.

After completing the ranking process, allotment is done which involves 5 steps. A particular number of students get selected for each allotment. As the number of allotments goes on increasing, your chances of getting selected also increases.

The final step is spot admission. It is conducted directly from the college for those who fail (if any), to report during the admission process.