CBSE

Yes, you can get it. You can apply for management seats in private colleges like Amrita, Amity, PES, etc.

You may check on these institutes like Institute of Technology, Guru Ghasidas Vishwavidyalaya (A Central University), Sant Longowal Institute of Engineering and Technology, Longowal, Shri Mata Vaishno Devi University, Katra and HNB Garhwal University, Srinagar.
As you are expecting a good percentage in 12th, you have good chances of getting top branches.

As last date for the PU is May 30, CBSE will announce results between May 25 to 30 and I am sure by May 28 results will be announced and so you can fill your form for the same .
All the very best!!

Hey Shuvam!
For admission in St. Xavier's College, Kolkata with B.sc Honours in microbiology, you must have Mathematics as a compulsory subject.
Kindly go through the link of eligibility criteria
http://www.sxccal.edu/admissions/SXCAdmission2018/UG8102/EligibilityCriteria.htm
I hope this helps.
AIMS PUNE admission procedure:
https://www.google.co.in/url?sa=t&source=web&rct=j&url=http://www.aimsinstitute.in/admission_details.html&ved=2ahUKEwjzkI3z44rbAhXZXSsKHV0zBR8QFjABegQIBxAB&usg=AOvVaw1eZhdLNBZb9OtnWVd8CcgI
AFMC admission procedure :
http://www.afmc.nic.in/#nogo22
Good luck Shuvam!

If you have any grievances, you can complaint to the concerned mail id given in the CBSE website.

Yes, you can get into PEC. CBSE Percent is also good. Go for it. You can get admission over there.

Yes, you are definitely eligible for JEE Advance 2019 because they accept the marks of NIOS board also and your 12th score is also good. Best of luck for your future and if there's any query, feel free to ask.

If you have done your schooling in Bihar and given your class 12th exam in Bihar, then you will be considered as outside Delhi candidate for JAC DELHI counseling and no matter that weather you go to any state, even Delhi.

For getting admission in a good college, you have to qualify their entrance exam. If you gave any college's entrance exam, then you can apply for admission. Or, you can take admission through JEE. If you have given any entrance exam, then you can easily get admission in computer Science cyber security. B.Tech. Good luck.