B.Arch Eligibility

High chances that you can land in that college with that percentile.

Yes you are. Hi, in NATA 2019 regulations, you have to secure at least 50% Marks in physics, chemistry and mathematics and an aggregate of at least 50% marks in board examinations.

Admission in Jamia Millia Islamia for B.Arch is through JEE Paper 2 ranks.

The last year opening and closing ranks at IIT, Roorkee in B.Arch female general category was 10503 and 12940 respectively. So you deserved for admission.

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 which NITs you can get. Wait for the final AIR declaration
Details:
https://www.shiksha.com/b-tech/articles/how-to-calculate-jee-main-rank-from-percentile-blogId-19953.

Placements: 100% placements easy for and average student to get placed with good package. The package differs upon CGPA and skills of the student.

Hi, yes you're eligible for admission in Jamia Millia Islamia. Admission forms will be available soon on the official website. For more details please visit https://www.jmi.ac.in/.

So, the basic criteria plan is to get top 20 percentile criteria.
Candidate must secure at least 75% in class 12 exams (60% in case of SC/ ST category candidates) or the candidates score should be in the top 20 percentile of the respective board. And you get a rank as a whole. That rank should be equal or near to that of the cut-off. Ramaiah's cut-off is of 250 (minimum) for general category. So yes, all the best!

There are less chances to go into this college. As there are already a few seats for architecture and this institute has the cut-off rank of 1721 for outside state students.
You may check Shiksha College Predictor to get more idea of which college you can get.
You can opt for any other college. Hope you do well in your future. Wish you all the very best.

No, you have to appear in the JEE Mains paper 2, then only you will be eligible for B.Arch.