B.Tech

Both B Tech CS and MCA meet eligibility criteria for working visa in most of thecountries abroad. For onsite assignment relevant experience is more important then type of degree.

Refer the link below :
https://engineering.shiksha.com/be-btech-in-electronics-and-communications-engineering-courses-in-gujarat-ctpg

Hi
If you know the basics of computer, you can pursue ECE as you will be taught the subject during the course, so do not worry much about it.

You can appear for JEE main thrice and JEE Advance twice that too in the consecutive years of completing your 12th so you cant appear for JEE after completing B.Tech agriculture

ITM university is the best in gurgaon

Check out the link below :
http://education.sulekha.com/agricultural-engineering_colleges

MCA or Master of Computer Application is a general Master's degree course related with computer application.It simultaneously deals with software and hardware functions and implementations.
On the other hand, a B.Tech in Computer Science and Engineering is a technical Bachelor's degree course, which

Marks is not the only criteria to get good package, sound technical knowledge is equally important, so focus on both to get good starting salary. The package also depends on the college and the type of companies visiting the campus so the highest package an range from anywhere between 6 to 8 lakhs

Placement depends on your performance in B.Tech, institute ranking and branch of engineering. Please confirm you engineering institute and branch in B.Tech for more appropriate answer.