B.Tech

BE in CSE will give you more opportunities.

Diploma is better because you might opt for Diploma in one stream and opt for BE in the other. By this way, you will open up more career opportunities for yourself.

The engineering colleges/ universities offering admissions through LEET are:
1. Punjab University – Chandigarh.
2. IP University – Delhi.
3. Delhi Engineering College – Delhi.
4. Punjab University – Patiala.
5. KIITS University.
6. Thapar Institute of Engineering and Technology – Patiala.
7. Government Col

Mathematics as a subject is only in the first year of engineering and it's almost equivalent to the mathematics that you have studied in class 11th and 12th, so it is not so difficult.

Yes, you can do that. Even, if you clear that exam, you will have to face interview in which they will keep stressing on, why do you want change your field?

Yes, BE is a good option. It will give you good job scope and career opportunities.

You can refer the below given link to find out the best colleges in Bangalore for B.Tech:
https://engineering.shiksha.com/be-btech-courses-in-bangalore-ctpg

Your educational qualifications are sufficient to get good job in Indore.
Why do you want to do ITI after B.Tech CSE?

You should go for Sharda University.

There is no branch in mba that relates to engineering. However, operations is the closest that can relate to civil