Civil Engineering

Go for NIT Warangal. It is one of the oldest and well-reputed institutes. In fact, the placements are also good.

Yes! You can do a Diploma in interior designing as per your interest, even after doing civil engineering. All you have to do is find a good college or institute that provides degree or Diploma in interior designing. Following are the names of some good institutions that provide interior design either as degree or as Diploma:
Pearl Academy
Lisaa schoolof design
School of Interior design
Fine arts and interior design institute
AD the design school
AAFT.

Hi,
Yes, you can apply for the course. Admission is through Centralised Admission Process of Maharashtra based on marks obtained in 10th class. Candidate must have passed Mathematics and Science subjects and must attain 35% as an aggregate in 10th.
Regards

COMEDK 2018 College Predictor
Use your COMEDK 2018 rank to see where you can get admission at the link provided below:
See the courses, colleges & rounds you may crack
The result is based on admissions data of COMEDK 2017
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https://www.shiksha.com/b-tech/resources/comedk-college-predictor.

You can get chemical engineering at NIT, Warangal & NIT, Rourkela, metallurgical & material engineering at NIT Warangal as well as NIT, Surathkal & NIT, Rourkela. You can also get mining engineering at NIT Surathkal.

Hi, you may check Urban Planning but you have to visit the university websites and go through each elective list and decide what is the best for you. Apart from this, you have to decide where to study. There is a lot of research you need to do from your end like explore universities, their admission requirements, budget, etc. Currently, from your question, it seems you have very little idea of these things. So first, do some groundwork.

Please refer to the link provided below for a detailed comparison between these two institutes for a course in civil engineering. You should be able to compare various features of these two institutes which should help you decide which college is better an where you would like to study. Regards. https://www.shiksha.com/resources/college-comparison.