I am holding:

Ans: With a JEE Main percentile of 98.86, your son can expect chance at getting into several NITs, especially for less competitive branches like Electrical Engineering (EEE), Mechanical Engineering, and Civil Engineering. And for CS he will get in low ranked NITs.

Ans: Branch is your choice. But she may get in low ranked NITs and IIITs.

Ans: He can try for the branches other than CSE and ECE in low ranked NITs. Secondly with a 92.75 percentile in JEE Main, you can likely get into some IIITs, but not the top ones. The specific IIITs available will depend on the category, branch, and the overall seat availability.

Ans: Yes, a candidate with an SC rank of 5880 in JEE Main has a good chance of getting into an NIT, especially for a core engineering branch. While some top NITs might have lower closing ranks for SC/ST categories, many other NITs will have opening and closing ranks within the 5880 range.

Ans: Good. While "COE" and "CSE" can sometimes be used interchangeably to refer to computer engineering and computer science, respectively, they represent distinct fields of study. CSE (Computer Science and Engineering) generally focuses on the theoretical aspects of computing, algorithms, and software development, while COE (Computer Engineering) emphasizes the hardware and software interaction of computer systems. Don't think of placement much. Study properly. Leave this servant oriented mindset and try to be a entrepreneur. This ghost of placements are injected the brain of children by the sad, bad and mad society.

Ans: Homestate? Category? Steam?

Ans: Mechanical Good chance in NIT Nagaland, Mizoram, Manipur, Puducherry, Agartala, Arunachal Pradesh
ECE Possible in NIT Meghalaya, NIT Sikkim, NIT Puducherry
CSE Tough in top NITs; possible in NIT Nagaland, NIT Mizoram, NIT Arunachal, NIT Puducherry (spot/round 5-6)

Ans: Yes, you can change from Biology to Mathematics in Class 12, but it depends on your school board's rules (like CBSE or state board) and whether your school allows the change.

Ans: If your family can afford the ?3L fees (maybe through an education loan), Health Informatics is a better long-term choice — both in placements and future scope.