IIT

CSE is the best engineering, but I will suggest that you choose the branch according to your interest. If you are interested in programming languages then opt for CSE.

You can surely get admission in new NITs and SRM.

Hello,
The admission into IITs for undergraduate programmes is based on the ranks in JEE Advanced.
For JEE Advanced, the syllabus is NCERT's class 11th and 12th. But the difficulty level is quite high.

Hello Nagesh,
No, you cannot. There are no lateral entry admissions in IITs and NITs till now.
So, you may opt for other colleges through lateral entry.
All the best.

I don't think IITs offer biotechnology but you can check Shiksha's website and use filters to see it if gives such course.

Go to Shiksha.com and use filters to find which IIT provides that course.

Hello Prasanna,
Undoubtedly IIM would be the best choice, and for that you will have to prepare hard.
If you are in your final year, you can choose to go for CAT 2018.
CAT has three sections:
1.Reading Comprehension and Verbal Ability.
2.Logical Reasoning and Data Interpretation.
3.Quantitative Aptitude
You can find the complete syllabus online.
Go through it.
Go through previous year question papers.
You can join coaching classes if you want to.
Good luck!

IITs i.e. Indian Institute of Technology are the best engineering government colleges in India having very good placement but are very hard to get into. Please upvote and feel free to ask more doubts.