B.Arch

The admissions are done on the basis of JEE Main rank so to get a rough idea about the college you can get through below link:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor.

Jamia Milia Islamia has a lot of reserved categories for students, especially for Muslim students, and then too for women in them. Also, the seat matrix there is dynamic. Though, your marks are sufficient enough to get into it for B.Arch, you can fill the requirements in counselling.

80 Marks in aptitude section? Or 80 marks in overall examination?

Hello sharu,
Though there is no huge competition for B. Arch at Anna University, your scores matter a lot for getting a seat. Your score is not bad, but it is not sure that whether you can get a seat at the SAP campus or not. Try your best at the counseling.
All the best.

Hello Dheeraj,
Yes, it is. The B.Arch and B.Plan course if offered by the SAP of Anna University, which is a reputed institute for architecture courses. You need to have a good score in NATA to get a seat at SAP, Anna University.

Some suggestions be:
1- A Complete Self Study Guide for B.Arch. Entrance Examination by P K Mishra
2- Steps to Architecture NATA B.Arch. Entrance Exam Paper Guide Paperback by Nimish Madan
3- Steps to Architecture: B.Arch. (NATA/JEE Main) Exam Guide Paperback by Nimish Madan
4- NATA and B.Arch. Complete Self Study Material by Ar. Shadan Usmani

Yes, you can get into B.Arch with these marks into DY Patil School of Architecture.
Since, the cutoffs are dynamic and this data is based on 2016, so it may change and things may not turn in your favour. Although, your admission is more in your favour.

You are likely to get the best colleges in India with such a big rank. I would suggest NIT Trichy, NIT Kozhikode, BMS College of Engineering, College of Architecture, Chandigarh and RV College of Engineering.
Note: Kindly check the least board marks for colleges as mostly for general, these marks are 75% in 12th.

Yes, there are many colleges which accept Mains paper - 2 as well, still there are many which accept only NATA. Some recommendations are BMS College or Engineering, NIT Trichy, NIT Kozhikode and RV College of Architecture.