JEE

Yes, you can get admission in RAIT based on JEE marks. You should fill in these options carefully in your CAP admission form. Accordingly, if you get allotted CS or IT, it's good. There is a high probability that you can get CS or IT.

Hello,
I hope you are doing well. You have very good marks and rank in JEE Mains paper hence you are eligible to get the admission in NITs along with your favourite branch. Go for councelling, fill NITs with top ranking preference and get the best one along with your favourite branch.
All the best.

Fiit JEE is too good for JEE Mains.

Only in private colleges! They do take admission on the basis of board percentage and donation as well!

You can get good branch in srm but the choice needs to be yours.

http://www.srmuniv.ac.in/admission-india/management/admission-procedure-admission-criteria
Please check if you match all the criteria for admission in SRM and according to your question this course is available only in the main campus. Have a look on the course available:
http://www.srmuniv.ac.in/admission-india/management/programs-offered

You can check on the college predictor that which colleges you are getting on the basis of your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

We cannot decide allotment to IHMs. It is based on numerous factors- No. of students appeared, no. of students passed, merit list, vacancies, reservation, demand for admission, etc.
But for reference, you could use past statistics (it is available on NCHMCT Facebook page). But that cannot be a solid reference line for this year's admission.

If you are really confident that you are going to beat JEE Mains the coming year, droping this year is a very good choice.

Yes, you can apply for JJ College of Architecture. I have no knowledge regarding COEP.