B.Tech

It is very unlike having studied the cutoff of last 5 years. But if you are in the category you should try.

Hi Chetan, the admission in SRM University is based on the entrance exam conducted by the university. But it is not for Diploma students as the eligibility is 10+2 completed or appearing for it .
For more details refer :
http://www.srmuniv.ac.in/admission-india/Eligibility/Engineering-and-Technology

Some IITs do offer robotics but not at B.Tech level. Robotics is offered as a subject when you approach for M.Tech in IIT Kanpur, Mumbai or BHU. But if you want to pursue robotics later, it is advisable to choose Mechanical, electronics or computer science at B.Tech level.

Bangalore is a better option for CSE as there are many IT company in Bangalore so they came for placement in nearby college of Bangalore. So, if you are there then you get placed easily.

Please go to the following link and check the participating institutions.
https://www.jeeadv.ac.in/

You can approach the university/college directly, and go with the proceedings. Some colleges in Germany accept the GATE score too, so that would help.

SAT is the only exam you need to take in order to study abroad.

No, you cannot appear for IIT-JEE after 2 years from clearing 12th.

Satyabhama University, Chennai is better than LNCT, Bhopal. Crowd quality is not good in LNCT. Also, placement is below average so I will suggest you to join Satyabhama.