JEE Advanced Eligibility

First of all, I tell you nothing is impossible, but as you attempted two times then it's little risky that next year you may crack the exam, as from next year, new pattern question may be asked, as only one paper is going to be held for engineering also, just like NEET in medical, so it is risky to do.
You can crack it, if you have really confidence that I missed the exam with little marks like that.
But, I suggest you not to waste one more year, as in future it may be questioned that where you spent these two year.
I strongly recommended you to join any college, because it is a matter of one year.

JEE rank and cutoff marks change every year. According to the last year's cut off if you score 85-95 marks in JEE Mains exam then your rank may be nearly 100000 or below or above and your eligibility to appear for JEE advance is according to this year's cutoff.

Yes, you are eligible for JEE mains, but not for JEE advance.

If your aggregate in PCM is above 60% (general), you are eligible. If you belong to OBC category, you need 50% aggregate in PCM and for SC/ST, more 4-5% relaxation.

Yes, you are eligible to appear for JEE Mains 2017.

You have to check the required percentage for IIT for up board .If you percentage are above the required percentage you will be eligible but if not there only one way that you again have to give 12th exam.

if you are general then no or if you are sc/st then yes!