Engineering Entrance Exam

Yes, you can get Sastra, Tanjavur under stream 2.
To know about stream 2 visit:
http://www.sastra.edu/index.php/2014-01-29-07-16-11 .
Go to the above link and click on FAQ 2017-18
I think you can get your answer here.

The best thing you can do is to learn computer courses. Since you want to learn computer science engineering, you need to learn that.
Computer science is a course in which there is a huge competition. So you need to be highly skilled to be better.

You have slim chances of getting admission in good colleges. You can check the available colleges at this rank by using this tool:
https://www.resonance.ac.in/reso/news/JEE-Main-Branch-Predictor.aspx

Hello Rahul, the preference order is :
1) BITS Pilani.
2) VIT Vellore.
3) Manipal University.
4) Thapar University.
5) BITS Mesra.
6) PSG Coimbatore.
7) RV.
If you get BITS Pilani, then go for it.
All the best!

The minimum eligibility in admission to any NIT, IIIT or GFTI and IIT is to get 75% in your board exams and to qualify JEE mains and advanced exams.
www.josaa.nic.in is the website through which you can apply for counselling.

Hello Amala,
Please specify your category, however if you belong to general/OBC category then as per your marks your chances are nil for getting any government colleges.

Hello Chetan,
Check here for more insights:
https://www.resonance.ac.in/reso/news/JEE-Main-Branch-Predictor.aspx
You may also consider Thapar University and LNMIT. You will get good branches there.

No, he cannot get any NITs, IIITs or GFTIs. So he can try any colleges that admit based on both JEE main scores and board exam scores.
You can browse the list of colleges that accept both these parameters for admission.

No, it is not necessary. Only if you want to get an IIT, NIT, IIIT, etc. you should write it.
These all are government aided colleges (central government).If you want to study in private universities like VIT, BITS Pilani, SRM then you have to write their entrance exams. They never see your JEE marks.
Then, if you want to get some good colleges where they accept JEE main scores and board exam scores, then to increase your chance of admission you may write it.
Otherwise, it is never compulsory to write JEE exam and you can get a good college for B.Tech through your board exam marks itself.

Your Diploma doesn't matter for JEE exam, if you qualify JEE Mains then you have to study from first year your diploma will not consider for JEE, but you got the benefit of OBC certificate.