IIT

Ritu, you can try for admission in private universities. You can not give JEE advance without appearing for JEE Mains.
These days we have so many good private universities too that are imparting quality education to the students around the world. They offer you admission on JEE scores/ tests conducted by them/ your marks in 12th. Some of these also offer good scholarships based on any one of the above mentioned admission criteria.
Check the websites of some good universities or call on their toll free no.s for more details.
Good luck.

Refer link :
https://www.shiksha.com/b-tech/jee-advanced-exam-pattern

Follow link :
https://www.shiksha.com/b-tech/articles/iit-admissions-blogId-12996

It varies from year to year. Also, it depends on the subjects you want. If you want CS in IIT then you need to work really hard and get a very good rank.

Yes, you surely can but you need to refer the JEE preparation textbooks. JEE portion is a little advanced from our CBSE portion. So doubts will surely arise but you can take help of Internet tutorials or guides. Even the students who take special coachings for IIT JEE preparation, self study for better understanding.

DTU Delhi, Anna University, PSG College of Technology, Manipal Institute of Technology, JNT University, SRM university in the order of precedance.