CBSE 12th

You can get admission for engineering, but during the time of placements, you will be facing problem because companies do not allow the students having marks less than 55% for the recruitment.

There are high chances that you will get in. Back when I started my engineering in the stream of IT, my class had the last rank of INR 66k. It is usually followed by Instrumentation and Production streams. You have not mentioned your preferred stream, if you are flexible in that aspect, I think the chances are even higher.

No my dear friend, you really have very poor scores in class 12th and to join BCA, you need to have at least 55% of 50% in class 12th, because that is the least eligibility criteria, which need to qualify and you don't have that, so you cannot join BCA.

Hello, I hope you are doing well. You can check the list of colleges including NITs and IIITs that you can get according to your marks and rank here. Use Shiksha JEE college predictor:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=7489993.

Check on the below list of colleges-
Atal Bihar Vajpayee Indian Institute of Information Technology and Management
B R Nahata Smriti Sansthan Trust
Government Shyamlal Pandviya College
government Maharaja PG College
R K D F School of Engineering
Shree Institute of Science and Technology
Barkatullah University
Sarojini Nadu Government Girls Post Graduate College
Government Motilal Vigyan Mahavidyalaya
Holkar Science College
Hitkarini College of Engineering and Technology
International Institute of Professional Studies
Devi Ahilya Vishwavidyalaya.

Yes, you can. Of course, you can apply for councilling here.

Companies do not ask for the marks in individual subject. They only ask for the aggregate of 10th and 12th class. Some companies allows the students who had more than 55% aggregate in 10th and 12th but some of good companies require more than 60% marks for the same. Hope this helps you
Thank you.

If you really want to become a doctor, then you should prepare for NEET. If you are interested in studying abroad, then prepare for GMAT SAT. There is need of good doctors especially neurologists in our country. Medical field provides a good income. All the best.