Gujarat

Hello Raju,
I am afraid, Diploma in a technical subject will not make you eligible for admission in 2nd year. You will have to begin from first year itself.

Hello Bristi,
Complete details are available in a link that I am attaching. Fundamentally though, domicile of Gujarat looks to be main criteria:
https://www.shiksha.com/b-tech/articles/gujcet-2018-exam-dates-and-application-process-blogId-14994

School of Science, University of Gujarat. All the universities in Gujarat have M.Sc in chemistry, select the one near to your place to save time.

Absolutely, you can, but for that, you have to get a Bachelor's degree plus crack an exam which is conducted by your state govt. and you can also try for UPSE.

NID, Ahmedabad is the best institute for design in India. If you are thinking to get in the same, you should get in without thinking twice. The faculty, placements and even the infrastructure leads every institute in the country.

The general eligibility is class 12th pass with 50%. However, the age criteria with the different colleges can vary. You need to check the same from the concerned college.