Architecture

You might get admission in some college for M.Arch. The eligibility differs from one institution to another. I would advise you to contact the colleges where you wish to apply and inquire about the eligibility criteria.

Yes, NATA or JEE Mains paper-2 is the compulsory exam for B.Arch.

Hi Deekeshita,
B.Des results will be out probably by next week.

Find the details here https://www.shiksha.com/architecture-planning/mah-march-cet-exam.

You have got a good percentile but you should try to get more percentile in the April exam so that you can get a better college such as NITs, IITs, etc.

Last year, the cut off was 27 for the Respective M.Tech seat, but coming to this year it may vary.

The final AIR will be declared after April 2019, considering the best score out of the two JEE Main attempts for all the applicants, hence based on current percentile we cannot predict for which all colleges you are eligible. Wait for the final AIR declaration.
Details:
https://www.shiksha.com/b-tech/articles/how-to-calculate-jee-main-rank-from-percentile-blogId-19953.

AAT (Architecture Aptitude Test) is an entrance exam for admission to the B.Arch programme offered by IIT Kharagpur and IIT Roorkee. Aspirants desiring to join the B.Arch programme available at both these IITs must appear in AAT. If you want to join IIT Kharagpur or IIT Roorkee, then only you have to appear for AAT otherwise not.

You have good chances to get admission with this score. Keep trying hard, and in meantime do keep eye on other colleges too to have a safe hand.