B.Tech

You can join B.Tech CSE course, but you have to give lot of effort to learn. You need to practice good questions on course related topics. Make good relation with faculty and good friends and take help of them. Take active participation in college coding club and in tech fest. You can also learn from Codeacademy, Udemy, EDX, etc. You need to be hard working. You can do it. Coding will be hard for you at starting but don't give up, it will become easy after you learn something. It will become easy with time.

No, you are not eligible for B.Tech in Amity University.

Here is the list of top colleges in India for automobile engineering
https://www.shiksha.com/b-tech/ranking/top-automobile-engineering-colleges-in-india/51-2-0-0-0

Please visit this link.
It will give all the important information for getting admission there.
https://www.shiksha.com/university/dr-d-y-patil-vidyapeeth-pune-52115/admission

You can take admission through lateral entry in B.Tech that will be in second year.

Naval architecture is more of a combination of engineering and design, which helps build all kinds of watercraft or structures. The below colleges are for Naval Architecture studies in Maharashtra. Phoenix Maritime Services (P) Ltd, Nagpur
College of Engineering Pune - Savitribai Phule Pune University.