B.Tech Computer Science and Engineering

Just check the course structure of the university website to see what all will be required in mathematics and prepare accordingly.

Hello Veda,
CSE and ECE are totally different both have different base. CSE will take you in the world of Computers and software whereas ECE towards electronics and semiconductors. Now, its on your choice if what you like the most. Choose one and go for it.
As your aim is to become IAS, you can be an IAS after doing this engineering but for better is suggest you to go for B.Sc if you are totally confident to go for IAS.
All the best.

Undoubtedly, CSE is the best.

There is no age limit. You should have your Diploma certificate.

Every subject is important because it helps in maintaining the overall percentage but subjects like design and analysis of algorithms, operating systems, computer networks, artificial intelligence and java programming should be given more preference.

CSE is better than it.

You can check the below mentioned link:
https://www.shiksha.com/b-tech/course/b-tech-in-computer-science-and-engineering-school-of-engineering-and-technology-ansal-university-gurgaon-751

Both are good, you should follow your intentions. If you are good at computer programming, it is better to take CSE. Otherwise, mechanical is much better.

No, it is not hard. All the languages have almost same logic. If you can clear the notes, then programming is not a big deal.

You will come across, C, C+, Java, Python, SQL, PHP, JSP, ASP and many more.