SRM Institute of Science and Technology, Kattankulathur

Yes, you can you must take part in counseling process.

You can join SRM University, Chennai as it has a good reputation and is considered to be a good private college for B.Tech. SRM University is one of the best institutes among top 10 private colleges in India.
So, be a part of it and do well in your future.
All the best.

SRM NCR campus is also good if you want to be in North. Otherwise Ramapuram campus is better than NCR.

SRM is quite good with respect to placements for CSE department where you just need to maintain a decent CGPA.

No, you will not get CSE branch for 55000 rank in the category A. Though you can get it through category C or category D where you need to pay a lot more than the normal fees same goes for electronics deparment. The fee will be around twice of the normal fee. You will get biotech or genetics department at this rank.

All 3 colleges are on the same level. I am a student of SRM so don't have much knowledge about the other two. CSE in SRM is quite good. If you want to get placed after your college then SRM is the place to be as you just need to maintain a decent CGPA. You have a lot of opportunities to learn and excel as the department is very supportive. So all over I can say that CSE in SRM is quite good if you're serious about it.

SRM, Amravati is better than Madras Institute.

Yes, it will provide through LEET entrance exam.

SRM University, Chennai is better than the other one.