Telecommunication

You can learn it from various institution, they offer a good programme, in BIG Data.

Yes, I think you will be eligible to change your subjects after 1st year, however, you should clarify with the admission authorities in your college. Since, the first year is a general course same for all students, you may be able to switch subjects in the 2nd year provided there is a vacancy in that particular department.
Regards.

Hello Atharva,
If you intend to get admission in an IIT then the answer is yes. This is so since IIT's treat Diploma as equivalent to 12th and hence you can appear for JEE Mains and JEE Advanced for admission. However, if your intention is for lateral admission then you will have to go through matrix of eligibility versus possible branches of engineering, available on website of DTE of Tech Edu Maharashtra.