B.Tech

Of course it is very useful but it is completely a different stream. One is technical and the other one is based on literature. Please choose wisely.

Well, I don't think so.

Yes, you have a chance of getting admission into Amrita University as you have a good rank. Please attend the counselling conducted by the university with all the necessary certificates.

Hi Avanish,
You have a chance of getting seat in your desired college with your marks. If you want to know in which colleges you get seat please go through the link and choose the best college that is suitable for you:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
All the best

Hi,
For more detailed information, you can see the below link:
https://www.shiksha.com/teaching-education/amp/rie-cee-exam

Yes, you can apply.
Eligibility for B.Ed:
At least 50% percent marks either in the Bachelor's degree and/or in the Master's degree in Sciences/Social Sciences/Commerce/Humanity. Bachelors in Engineering or Technology with specialisation in Science and Mathematics with 55% marks or any other qualification equivalent thereto.

It's not possible for you to get admission in any of the NITs with 73 percentile. I would suggest you check out the college predictor tool:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

Well, it is not necessary to have knowledge of C/C+ if you are pursuing CS but you need to learn this in your 1st year as CS students, these are the basic languages and you should know these.

Yes, of course. You can pursue either BCA or B.Sc in IT or you can simply self-educate yourself through online material, offline books and coaching and training centers.