Agra

For B.Ed in Hindi, you need to have BA with Hindi from a recognized university with 50% marks (or) graduate (BA/B.Sc/ B.Com) along with intermediate with Hindi from a recognised board and BA Level Diploma in Hindi from any institute recognised by the Govt. of India (Vidwan, Ratna, Shastri, etc.).
At Graduation level, one of the subjects of Social Study (History, Geography, Political Science, Social Science, and Economics) is compulsory.

Hi,
If you want to study Bachelor's degree, your academic record from 10th to 12th will be checked. Change of board is fine and I don't see any reason why it should have a negative impact on you admission. You must meet the admission requirements importantly, have good grades and take the IELTS.

Different colleges have different criteria for admission into their B.Sc courses. Some institutes have written examinations for admission into their B.Sc courses while others may require a minimum cut-off percentage for their 12th exams. 58% should be good enough to get into most institutes for B.Sc. However, students are advised to check university admission criteria individually.

You can refer the below link for college comparison:
https://www.shiksha.com/resources/college-comparison-231131-33087

You must have passed 10+2 from a recognized board.
Maximum age should not exceed 21 years on the 1st July of the year of admission except for female students.The upper age limit can be relaxed by three years for SC/ ST candidates.
For more details visit:
https://www.shiksha.com/accounting-commerce/course/b-com-honours-faculty-of-commerce-dayalbagh-educational-institute-agra-30773 and http://www.dei.ac.in/dei/index.php/programmes-of-study.

It was on 26th of July. Sorry to say but you have missed that. I can say that just contact one of the counsellors there and get better knowledge about that.
God bless.