B.Com

You graduation marks are required at the time of admission. Try to clear all your backlogs (if any). Maintain the 50 percent aggregate throughout your graduation.

Every field has its own scope. Firstly, try to find out the areas in which you are really interested. The next step should be to gain knowledge about that particular field. Finally, opt for the course which will help you to advance in the field of interest.

For taking CAT exam, you must be a final year graduate student or you should have completed your graduation.
So don't worry about 1st-year marks, you can improve it in coming years if you put some effort.
For CAT or other management exams, degree marks are not considered. You can attend it, but it is up to the college where you take the admission, marks are compulsory or not.

Yes, you are eligible for CMA, but CMA is tough but nothing is impossible.

Students with science stream in class 12th can do B.Com but arts students cannot pursue B.Com.

Students with science stream in class 12th can do B.Com but arts students cannot pursue B.Com.

Students with science stream in class 12th can do B.Com but arts students cannot pursue B.Com.

You should complete your B.Com first and then only pursue another course. This would help you in becoming an expert in a particular field.

There is a PG Diploma in psychology available in different institutes. It is better for anyone, who are new to psychological studies. Distance educations are available for this course. It will cost you below 35000 or 40000, I guess.
Please refer to IGNOU, they provide options for the distance learning in psychology.