BBA

Yes, the institute does provide courses in aviation. Please refer to the link below and select the course you wish to enroll for:
http://www.hindustanacademy.edu.in/academy/business

No, IGNOU offers BBA only in Retail. They have their special program for Retail BBA and they don't have any course for General BBA.

After BBA if you want to pursue your career in MBA you have to fill all the Forms for Entrance of MBA/PGDM PGPM.
Also there are some other competitive exams where your can try for some government exams which you can check on government sites.

Yes, Apply for Final Year Exams with your last two year passing certificates.

Diploma is good.

You have to have confidence in yourself. If you can't clear CAT, you can pursue LL.B. It is a good option for BBA students.

Hi,
Aimfill International - BBA in Airline and Airport Management: Placements (as provided by college)
Companies / Recruiters who visited the campus
Air India blue dart IndiGo Airlines kingfisher Qatar Airways Spicejet
You can refer the link for colleges in Kerala for BBA in airline management:
https://www.shiksha.com/aviation/colleges/colleges-india?uaf[]=base_course&ts=26575955&rf=filters&bc[]=30

It solely depends on your interest. Both are very good under graduation streams. If you wish to pursue a career in commerce, you should opt for B.Com (Hons). If your interest lies in understanding the business from every aspect, you may wish to pursue MBA later, BBA will be a good choice.