IIIT Sri City - Indian Institute of Information Technology

IIIT, Sri City is better then other two. It is mentored by IIIT, Hyderabad and follows the same curriculum as a result of which this year placement were at par with middle level NITs and will surely grow better in coming 3-4 years.
Good luck.

If you belong to open category I think it very difficult to get a seat. Even you can apply for JOSAA options entry because you might get a home-state NIT.

Can I know the rank, because mostly the colleges are predictable only by the rank. If you got higher rank also I suggest you to go for JOSAA because in the previous year many seats were vacant due to lack of knowledge during options entry. If you're lucky enough you get one of them.

Can I know your category rank, if there is any?
If you belong to any category other than open category, there is a high chance of getting ECE, based on the previous cut-offs of the college.
If you belong to open category, I'm afraid there is only a little chance of getting a seat. If you're lucky, you may get a seat in the college in the spot round.
Last year, nearly 20 remained empty after the final admission of the students.

With your rank being 18433 in JEE Mains, you can get a seat in IIIT Sri City, keeping the previous year cutoff in mind. 50% of the placements has been completed for 2018 passing out batch and still the placements are continuing. The packages are good and will improve over the period of time.

It's never about the college it's about your interest. In which field you want to build your career. All the colleges are good if asked specifically go for government. Institute because there we get quality in teaching methodology.

Iiest shibpur civil in my view for sure.

Yes, there is one scholarship known as "TFW" (Tution Fee Waiver).
In this your semester, fee will pad by government.

Yes, you can get a seat in IIITs.

We do not do the comparison here in this platform. But our being mentored by IIIT Hyderabad, follow 90% of their curriculum and we are research based institute.