Diploma

Yes, you can pursue Diploma in airport management from Akbar Academy of Airline Studies.

Of course, you can switch your branch. But, think twice before switching, because you will be a complete fresh person while entering Engineering with no knowledge of mechanical, while you will be having plus point, if you continue with your same branch.

Hi,
B.Sc is considered equivalent to graduation. Afterwards, you can directly get admission to a Master's degree. On the other hand, a Diploma is not considered as graduation and lacks credibility too. Also, with a B.Sc Degree, you have an edge to get into teaching industry.

To get into IIM, you need to write CAT exam. After CAT, if you get the eligible percentile to get into IIM then you have to face a personal interview in any of the prescribed IIM from your choice based on the marks. Sometimes, even you get 100 percentile in CAT, you may not get an IIM, all you need

Yes, JNTU offers admission to Diploma students also, the one who is allotted seat based on his/her ECET rank can directly join in the second year with regular (4-year course) students.