NIT

Since EWS category is newly introduced, but you have chances in good branch and good colleges. So, you can go for counselling in GFTI, CFTI or reputed state government college.

No, you can't get NIT with this percentile in JEE Mains.

Yes, sure your admission is confirmed in NIT because you belong to the SC category.

It is hard to get CSE with this rank in any government college but you may try for NITs, Silchar, Mizoram, Meghalaya, and Nagaland.

IIIT-Bangalore is best for CSE than NIT Silchar, you can compare through the placement record.

No, admission to NITs and IIITs is based solely on your JEE Mains score. And, a minimum percentage of 75% is required in 12th boards. A score of 260+ is a power score in JEE Mains which is required to get admission into an IIIT. For NITs, if you are ready to take any branch that is offered to you, i.e., if you are only concerned with the name of the college then a score of 150 in JEE Mains is enough. On the other hand, if you want a high profile branch like CS then a 200+ score is a must.

Yes, with this score in JEE Mains Paper 2, you can easily get NIT.

Hi,
Yes, you can get admission in your home state NITs, but as per your score, it will be possible only in third round or spot round only. You can predict your possible colleges here:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
Best of luck.

Yes, you can get admission in NITs with this rank. To predict your possible colleges, I would suggest you click on the link below:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor