CMAT

For this year it seems not possible because the college seats are full but you can visit the admission office. They can tell you if it is possible.

The colleges requires CMAT for admission as per the rules stated. Hence, you will not be able to get admission otherwise.
Please see:
https://www.shiksha.com/college/r-b-institute-of-management-studies-rbims-thakkar-bapa-ahmedabad-31355?q=R.B+Institute+of+Management+Studies+(+RBIMS+)&rf=searchwidget&landing=ilp

You will have to give a departmental test for which you need to fill an online form on:
http://www.amucontrollerexams.com/courses.html
Test Paper Details:
There shall be one paper comprising 80 questions with the following breakup :
a) 70 Objective Type Questions (Multiple Choice): 140 marks.
b) 10 Short Answer Type Questions: 60 marks
Entrance syllabus:
You can download it:
http://amucontrollerexams.com/syllabus/msc_botany.pdf

Looks difficult. Nowadays, most MBA colleges give admission based on the scores received in admission tests which could be either CAT, MAT, CMAT or their own tests.

Yes, as you have itself declared that you got the college in second round. I would ask you to try for C. E IIMP for the remaining round you may get in to it.

Please see:
https://www.shiksha.com/mba/exams/cmat?q=CMAT&rf=searchwidget&landing=ep.

Yes. CMAT is necessary to apply for admission in MBA programme.

Fees is equal for everyone. If IMS has allotted you the admission seat they would also given you the fee structure letter or brochure on which how much you have to pay and when and through which mode will be written.

Sorry dear but since your rank is way below so I don't thil you will get admission in ims, because they allot seats on rank basis.