BITS Pilani - Birla Institute of Technology and Science

IIT is the best. BITSAT is the second choice.

No, BITS exam is easier than IIT. IIT exam is tough that every year around 15 lakhs candidate appear for it. The number of participants is directly proportional to toughness of the exam.

Welingkar is the best option among these colleges and has a good brand value in India. PUMBA has a good ROI. Welingkar, Mumbai campus is an older one and preferred for management studies.

The eligibility criteria is BE/B.Tech or post graduation degree from a recognized university or any integrated degree from BITS. BITS integrated degrees are of four years duration. As your graduation degree (B.Com) is of 3 years duration, you are not eligible to seek admission in BITS Pilani.

You may refer to following link for article on campus placement at BITS Pilani: https://www.shiksha.com/bits-pilani-placement-report-2014-article-9417-1. This will give you an idea about university placement record. You must include university in your wish list.

I would suggest you to avoid VITS - Dubai campus as it has poor ROI. You can try for:
1. BITS – Pilani.
2. BIMTECH – Noida.
3. BIMTECH - Bhubaneshwar.

BITS is amongst the top colleges in India. According to me, you should go for BITS, Pilani.

Placement wise, BITS Pilani is the best.

BITS - Pilani does not offer any course for aeronautical engineering.

No, you would not be able to surpass the cutoff (which is minimum of 300 out of 450) if you only prepare for the 12th syllabus. The 11th syllabus is as important as the 12th and carries equal weightage (might vary a little bit). It is advised that you prepare both the 11th as well as 12th syllabus. The questions would be direct and easy. Just try to focus on the important topics. Hope you do well.
Best of luck.