Geography

Yes, you are eligible but the majority of the institutions and colleges conduct entrance for even these courses.

Even if you are from reserved class then also I don't think you'll be able to get admission.

Yes, you can get Shivaji College. Your marks are good. There is another 1-2 percent relaxation at DU for female candidates. Your name would come in the 2nd or 3rd cut-off.
All the best.

You can refer this link for best private colleges for geography honours by comparing their ratings and other necessary details:
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/humanities-social-sciences/geography/colleges/colleges-india&ved=2ahUKEwjasKPPnYTjAhWUfH0KHQi-BYYQFjALegQIBRAC&usg=AOvVaw3q8qjkRywAqN4mhTicRvda&cshid=1561451823790

You may check this link :
https://www.shiksha.com/university/Tripura-university/tuet-exam-syllabus

The best of four percentage for your respective marks for B.A. Geo (Hon.) will be 75.5%.

Yes, take the subject combination assuming that you are talking about class 12th, you can take these three subjects. If your school allows it and if not then probably can't talk to them and tell them that we will give exams in externally, if it is allowed in your school. But, it is not allowed in all the schools and if you question is related to college level then definitely in BA Programme you can take these three subjects combinations, but depends on your college or university.

There are total of 46 seats for BA H for geography. If you belong to OBC category, then chances are higher that you will get seat there with a minimum of 60% marks in class 12th.

While taking admission for any BA Course, your overall Percentage is considered not the individual subject marks. So, your low geography marks is not a problem. You can get admission in any college for BA according to your Percentage.