Architecture

Architecture has wide scope nowadays.

Yes, you can pursue Masters in mass communication after completing B.Arch. But you will have to appear for entrance tests for the same.

Hi,
You are not eligible for the exam. As per eligibility criteria, the candidate must be aged between 18 to 27 years as on 1 August 2016.

Lateral entry is not available for B.Arch. You can take admission through lateral entry into B.Tech.

Instead of B.Arch, you can take admission in BID (Bachelor in interior design).

To get admission in NIT, a candidate must appear for JEE Mains. Unless, you appear for the entrance exam you won't get admission in National Institute of Technology. The eligibility criteria for entrance exam is class 12th with PCM as the subjects.
Apart from IIT and NIT, most colleges in India offer lateral entry for Diploma students. These colleges do reserve some seats for lateral entry students.
All the best.