India

Hello Sanketh,
It's not the issue of percentage in your 12th that will matter for admission here but what matters is your domicile. If you have domicile of Tamil Nadu then you can think of getting admission. But there are enough colleges in Bangalore itself offering Aeronautical engineering branch. I am attaching a link that will give you the required information.
https://www.shiksha.com/b-tech/ranking/top-aeronautical-engineering-colleges-in-bangalore/49-2-0-278-0

I don't think there is any such college.

Yes, physics students can apply for the wildlife science course at Wildlife Institute of India. You are eligible for this. Also, if you are looking for something quick, there are a few short-term courses that teach you all that you learn in a Master's course like PRiMER, a week-long certificate course offered by Gubbi Labs twice a year. Do check out their website and see if they have any courses coming up soon. It is an extensive and intensive course on ecology and wildlife from the research perspective.

Yes, you can get a government college but its depending upon in which stream you are interested.

I checked last year's cut-off and could not see your rank. Do check it this year to know any change in the cut off.

According to last year's cut-off, you can get admission in 2nd round of counselling for 2nd shift.
It may change this year. So, keep a check on IP's site for the cut-off release date.

Yes. You can get really good jobs outside India after completing this course. But, this would depend on how well you learn during your training. And the skills you develop.