B.Tech

If you want to teach the students interested in the preparation of IIT there is no restriction that you have to choose B.Tech or B.Sc. You can do either one of them. There are many B.Tech holders who are even pursuing M.Tech and becoming lecturers. So it's up to you in the field you are interested.

No, if your father has Dubai's citizenship then you can get a college by NRI quota.

Yes, of course, there are many colleges offering distance education. You can also do distance education in some of the top colleges in India. I would suggest you to visit Shiksha.com and find the right college for your distance education.

Actually, you can try for jobs in software field, you may find good jobs there.

Yes, you can do it. Only 50% aggregate is required in your UG course for the same.

Usually, a minimum of best of four 97.5%/97.8% is required. That's the minimum. Scoring a 98 or above would be on the safer side.
Maths is required as one of your subjects in +2, and you need to pass in it. However, it's usually not calculated in the best of four.