Architecture

No, you can get into IITs for B.Tech or any some other Science courses or integrated courses.

Yes. It also depends on your board marks.

Here is a link that can help you:
https://www.apnaahangout.com/be-btech-agriculture-engineering/

Yes, you can easily get any of the NITs for B.Arch but getting good NITs would be somewhat difficult for you, otherwise, you would definitely get the one till the last round of counselling.

It is just fake news that you have got and nothing else. Both the institutes are participating in JoSAA 2018, as usual.

Yes, Raheja College of Architecture accept the JEE Mains paper 2 score. So, keep going. Best of luck.

Hi Abdul Rehman, Eligibility Criteria:
Candidates shall be eligible for admission to the first year of the Bachelor's degree programme in Architecture or Planning if they have obtained at least 50% in aggregate with mathematics as a subject in the class 12th or qualifying examination. Admission Guidelines:
Admission to the Bachelor's degree programme in Architecture and Planning will be made through Joint Entrance Examination (JEE/JoSAA) conducted by the Central Board of Secondary Education (CBSE) strictly on merit. Regards.

Yes, they accept JEE paper 2 score. You can try to get admission. Apply for admission, you will definitely get the college, if your rank is under the requirement.
Good luck.

Dear Anju, as per their website, they don't offer B.Arch.
Check the link below-
http://www.rgit.ac.in/faculty-accordion
Good luck.