Colleges in Manipal

Yes, you can get CSE with that score. You will be eligible for a scholarship only if your rank is below 1000 in the Manipal Entrance Exam.

If you want to opt for B.Tech then do study till class 12th. It will prepare you for the coming years of your B.Tech. See if you want to end your school in class 10th and start pursuing higher studies, that is fine but it is your choice. Since you are saying you want to do B.Tech then I would suggest you complete your 12th and then directly do B.Tech. You can opt for Diploma after 10th and then do B.Tech through lateral entry.

You may not be able to get a seat in ECE in the first round of counseling itself, but I suggest you give your name for waitlist and also go for the successive rounds of counseling. You may be able to get it.

Yes, you will get ECE in Manipal University with your rank.

BITS Pilani is a better option over MIT Manipal.

It is difficult to get Aeronautical with that score since the cutoff has been going higher every year. You should definitely try for multiple rounds of counseling and giving your name for the waitlist. Considering the increased intake of the branch, you might be able to manage a seat.

First of all congratulations for your results!!
If you get that there is no issue of branch. You should take as per your field of interest. You are more likely to get all good branches like CSE,ECE and aeronautical as well. You can try for that.
Hope this helps you.