Manipal University, Jaipur

Yes, eligibility criteria to get an admission in any undergraduate programmes is 10+2 or HSC in any stream with certain predefined percentage.
BBA is also a 3-year undergraduate program.
Admission percentage and criteria differs from university to university.
For Manipal University-Jaipur, you are eligible only you should have minimum 50% marks in 10+2 in any stream.
Go through this official link of Manipal University, Jaipur:
https://jaipur.manipal.edu/muj/admission/indian-students/who-can-apply.html

You can login to www.mext.in from there you can find all previous year question papers of the stream you needed.

For which submission are you asking for?

The minimum marks required is 75 percentage for taking admission in better college.

Yes, they are both different and are located at different places. Their administration is also different. One is known as SMU widely.

MBA has recently been introduced in the campus.So the placements won't be up to that level but on an average its good.

Hi, Manipal Jaipur is more preferred than Amity.

Yes, it is valid but not everywhere. Medical entrance exams like
NEET and a few government exams don't allow NIOS students to appear for the exam.

Yes it might be a better choice.