B.Tech

Both are good but the 1st preference will be Chandigarh University then CGC. Good luck.

Yes, learning method is effective and different.

Yes, entrance exam of BITS Pilani is more difficult than VITEEE.

Your rank is good but not enough to easily get MNIT. But you can get biotechnology and other branches but not CSE/IT. Try your best and fill the JOSSA admission form properly. Give college and branch preferences properly. Good luck.

It depends on the university under which you will be graduating.
Mumbai university implements 7 subjects in each semester for the first year.

I don't know about this year's results. But I think it would be very difficult to find a college in Mumbai, if you do not belong to a reserved category.
Furthermore, going through the DTE processes, rankings and seat availability, you can find out.

Biotechnology is a branch with good scope for higher studies. Unfortunately, the placements are not at par with other branches. Most of the placement is in mass companies go with an average package of 3.5 LPA. But, VIT and SRM provide almost equal opportunities.