M.Tech

No. Only B.Tech and M.Sc. Are eligible. As u study only about geography. Out side. But B.Tech and M.Sc. Will study deeply.

For M.Tech, you should be B.Tech graduate, then apply in college/university. M.Tech from civil engineering has more option i.e., Structure, geotech, environment etc.

First, it depends on your interest level on the Branch. Next, is the duration of course. Are you okay to spend around 5+ years in the same course, and specialization at a stretch? If you are inclined to take up career in IT and Data-Science, Machine learning etc., then better opt for integrated course. ECE will be a bit tough, when compared to IT, and if you are very keen to go for ECE related jobs, then you can opt ECE from ISM. Keeping in view of placement opportunity and coding environment, it would be better if you to go for IIIT integrated course.

Yes, after completing your graduation you can join M.Tech biotechnology. As after graduation you will be able to study M. Tech. So, you can try to get admission in a good college.

Admission is based on the rank obtained in JEE Mains score. Interested candidates can apply online/ offline with required information. Please check for your eligibility to pursue this course from the criteria mentioned at the link provided below:
https://www.shiksha.com/b-tech/course/integrated-b-tech-m-tech-in-electronics-and-communication-engineering-international-institute-of-information-technology-bangalore-hosur-road-291407

Please specify the entrance exam for which you require sample questions, so that I may be able to populate relevant details regarding that test. Some of the popular M.Tech Entrance Examinations in India is mentioned at the link provided below:
https://www.shiksha.com/engineering/articles/m-tech-entrance-examinations-in-india-blogId-12539.