BBA

Delhi University affiliated colleges are best for doing BBA / BMS / BBE. Among various colleges offering these courses Shaheed Sukhdev College of Business Studies is the best college for graduation degree in Management. Graduates of SSCBS are treated on par with Tier II management colleges. SSCBS students get very good and high salary placements.
You may refer to following link for list of other top BBA colleges in India:
https://www.shiksha.com/bba/ranking/top-bba-colleges-in-india/93-2-0-0-0

The best campus is the old campus of Symbiosis, Pune.

You can prefer IGNOU or Pondicherry University or if you are capable of going with NMIMS or Symbiosis then you can prefer the same.

If you want to pursue MBA then do it from any college which has good faculty. The course fee is almost 82k per year in MIT whereas you will get other ordinary colleges in and around 15k in Mumbai. Yes, it is cheaper as compared to Symbiosis. Symbiosis charges around 250000 per year. BBA is absolutely not necessary for MBA.

You should secure minimum 75 percent and have more than 6.5 in IELTS. You should have enough funds for your education. You will also need to qualify GRE with a score of 315 or above. The approx. cost per year in Singapore is 20 LPA. The same will be the case in UK and Australia. US and Canada will be more expensive.

B.Tech is better than BBA.

It may vary between 1.5 LPA to 2.5 LPA for a BBA fresher student.

Retail Management is an important part of consumer business. Without retail no business can stand. Also, there are huge retail stores and supermarkets coming up. So retail management is a good course but since digital marketing is right now on high end, so retail is decreasing but retail will never end up.

There are many things you can do according to your choice and interest:
1. Engineering (CBSE - JEE Mains & ADV & State)/ Private
2. Medicine (CBSE - NEET & Domicile state )/ Private
3. Agriculture (ICAR & ". ) BIO/MATHS + UNIVERSITY
4. B.Sc ( Physics , Biotech , chem)
5. B.Sc ( any other subjects)
6. BBA , CLAT, ARTECTURE.
7. BANKING
8. Have a startup
9. NDA
It's is advisable that you must search and then only decide what you want.
All the best.