Architecture

Hi,
Please refer to the link provided below for details on admission criteria and eligibility to gain admission into the college of your choice. Your 12th results seem to be fine but your NATA score is low. You will get a more accurate picture if you get in touch with the college admissions bureau. You could also try for admission through management quota.
Link: https://www.shiksha.com/college/sir-j-j-college-of-architecture-mumbai-24830

CENGAGE is the best textbook for maths and physics. NCERT and Pradeep are the good choice for chemistry.

Please refer to the link provided below for a detailed list of colleges which offer Diploma in architecture. Details regarding admission, entrance exams, etc., are mentioned on the page with the link below. However, most colleges require a valid score in the NATA exam with a passing grade at the HSC level.
https://www.shiksha.com/architecture-planning/colleges/colleges-india

Yes, every PG courses requires a minimum percentage from UG course. Irrespective of which course you wish to choose.

Yes, you can appear for the NATA exam after completing your HSC.

Some of the popular textbooks for B.Arch undergraduate field of study are as follows:
1) Professional Practice of Architecture (A Text Book for B.Arch Students)by Prof. S.C.Garg & Dr. Yogesh K.Garg
2) Drafting Fundamentals & Standardsby Dorota M. Goede B.Arch.
3) Green Building Fundamentals A Concise Summary of Leed (R) Building Certification and Professional Accreditation Systemsby Goede B.Arch., LEED Green Assoc., Dorota M.
4) Advanced Engineering Mathematicsby H K Dass

From 2017, it is compulsory to have science stream to take admission in architecture.