Engineering

Hello Souvik, it's tough to say as to how cutoff percentiles will play out in this year's JEE Mains. I am attaching last year's cutoff percentiles for different categories. You will need to decide as to whether your percentile is good enough for your aim of not. Cut-off for JEE Advance
Candidates having at least 90.3765335 percentile will be eligible to appear for JEE Advanced. For EWS students the cut-off is 70.2435518, for OBC it is 72.8887969, SC - 50.1760245, ST - 39.0696101, PwD - 0.06185224
Best wishes to you.

Hello,
You have done B. Tech and want to do B.Tech again. Yes, you can do it by taking admission in colleges where there is no age restriction. Best wishes to you.

Hello,
The last year's cutoffs were as follows:-
Cut-off for JEE Advanced
Candidates having at least 90.3765335 percentile will be eligible to appear for JEE Advanced. For EWS students the cut-off is 70.2435518, for OBC it is 72.8887969, SC - 50.1760245, ST - 39.0696101, PwD - 0.06185224
If you expect these to remain similar, then you need not appear in JEE Mains again for improvement. If you feel that this year, it will increase then you must appear again to improve your percentile in remaining attempts. Best wishes to you.

Yes, because the maximum Attempt you can give Is 4 attempts.

No, you are just left behind by.50 percentage of getting CSE /ECE in any NIT because 85 to 95 Percentage is required fir the same.

Yes, but you should have an interest in this Otherwise you will suffer in near future.

The average package of INR 4.5 lac per annum to INR 6.5 per annum.

Yes, but you have to SEE what are the criteria for such colleges which Gives admission on this Much rank.