Colleges in Telangana

According to your percentage, there is chance to get admission.

No, you can't do. You have to wait for a year because the minimum age for PG Diploma should be 20 years.

It is quite possible, you may get seat in second or third counseling, best of luck.

Your question is, which is the best IHM mentioned in your question in terms of placement. I have arranged them in ascending order for you.
IHM Goa
IHM Hyderabad
IHM Kolkata
IHM Chennai.

No, they only give admission based upon the entrance score.

If you scored that much marks, then you have to appear for test which is organized by GL Bajaj, and if you are able to qualify, then only you can go for CSE.

You won't get seat in JNTUH with 28000 rank as it is very high and it doesn't meet the eligibility criteria. So try for another college. All the best.

If you want to do MBA/PGDM, Agribusiness Management is the course for you. IIMA offers Food and Agri-business Management.
I am a Food tech graduate, and I have no regrets of doing PGDM from MANAGE in ABM.

For that, you need to score at least 80percentile to get a call from IIMA. For MANAGE, it all depends on cumulative scoring. Yours marks till now are good, and being from Agriculture course, you have high chance of getting a call. Yes, confirming a seat will be easy for those with 80percentile above in CAT. So study smart, score your best in CAT2019 to take admission in the batch of 2020-22

Please use JEE Mains college predictor tool for better results
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor&ved=2ahUKEwi1pZzErb3iAhUQX30KHbopA0QQFjAAegQIBhAB&usg=AOvVaw1N9BzFtyUCP4JU-2UQHQ0H