Colleges in Vellore

Your VIT branches are decided by VITEEE. Hence, apply for VITEEE and qualify it and check that results to see which branch you get.

Don't take civil through management quota, as there are no placements in civil branch.

You can get any branch in VIT-Chennai campus.
For Vellore also, you can get most of the branches (maybe except CSE).
Yes, you can also get ECE in Vellore.

It's of no use to take civil through management quota, because there is no placement for civil branch in VIT Chennai.

You'll be getting your placements only in the final year and not before it.

Integrated programme are only for Software Engineering course and the application is common as for other B.Tech courses. You will have to qualify the exam and then select.

I'll refer you to join B.Tech CSE rather than integrated 5 year course because if you change your mind in 4th year of your graduation seeing that time scenario then it will be better for you to join MBA or by qualifying GATE you can join any of the PSU because joining integrated course is only beneficial if you have clear goal to join in research or be a professor in any college.

Obviously, your placement process will start in the final year of your course.

It depends on the group he gets too. According to my experience, he will get group 4/5 that too in Chennai campus.