JEE

Yes friend, You are eligible to appear in JEE Mains. For 2020, candidates who have passed their Class 12th Examination or any equivalent qualifying examination in 2018, 2019 or those who are appearing for their class 12th Examination or any equivalent qualifying examination in 2020 are eligible to

Yes, you are eligible for Thapar Institute via Mode 2 admissions as in that case u must be JEE Mains appearing to be eligible for mode 2.

Sastra score is calculated by 25% of the Mains marks and 75% of the ipe marks so score will be 90.725.

You can try for counseling. There is a chance Maybe get NIT's till or in spot round.

May you Please tell your JEE Mains Rank. Although I think You will Get CSE in Lower NIT's for sure. I am sending you a link where you SEE previous year statistics of Cutoff For CSE branch and Other useful information related to your query. Please check it out. link-https://www.shiksha.com/b-tech/jee

Yes, I hope that you'll get admissions. Let me first tell you about the Admission process.
1) JEE Main Score through OJEE Counselling in which your rank must be within 1lakh - 3 Lacs
2) Management Quota
3) you can give CVRGU Entrance Exam 2020
As you have 3 option to get and study at C. V. Raman Global

No, it is difficult to get into EEE, MECH, CSE but during the sliding process after and before admission you can get into it.