Colleges in West Bengal

No, but don't know why JIS College's rank is so high in local newspaper ratings, may be it is paid promotion but from study point of view there are many other colleges which are better than JIS.

No, as the admissions in NSEC are through JOSAA counselling and you don't stand eligible for it as you have not given JEE Mains. You should now left to go for private universities having their own entrance exams.

The fees structure of Rukmini Devi Institute of Advanced Studies for BBA course is 2.86 lac rupees that is 95.4K per year and the course duration is three years. For management quota seat, it all depends on college to college.

No bro, but if you wish, you can join through management quota. Else if you want to join any other Techno India Group college, you can visit the main branch and have a talk with them.

No, but if you want to study in any other Techno India Group college, then you can visit the main branch and have a talk with them.

Yes, but visit TIU campus once. TIU is good but Makaut cllgs are more valued. Try Msit , Netaji subhas, TICT or any other Techno India college from Makaut.

Yes you can get CSE and other branches as well. Your Rank is good. Use the JEE Mains College Predictior for Predicting Colleges you can get based on your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
Also research about Colleges you are interested to take Admission in. See there last year Cutoffs. See according to your rank can you get that College. Best is to use College Predictior. Good Luck.!

Leaving behind your OBC B rank, if I only consider your GMR, then also you will get into any stream in JGEC. Keep CSE in first of priority list, even if you don't get CSE in centralized, you'll get it in decentralized counselling.