Engineering Entrance Exam

You can easily get CSE in UIET. You won't get any branch in PEC.

Obviously it is JIIT, Noida.
Second priority will be JUIT, Solan
And, last will be JUET, Guna.

Yes you can. Wait for the common admission process.

I guess, it would be a bit difficult for you to get a branch in SGSITS, but you can wait till last round. You can also check last year's counselling results, it will give you a better idea.

Just go for IIT, Maan after that think of UPSC an all, but if your main goal is UPSC, don't go to IIT.

The admissions in Shri Ramdeobaba College of Engineering and Management, Nagpur are done strictly on the basis of merit and in a transparent manner. College has not authorized any agency or agent for admission of students. In this regard, parents and candidates are sincerely advised not to fall a prey to unscrupulous agents or agencies.
https://fe2017.dtemaharashtra.gov.in/StaticPages/HomePage.html.
Check this link. All the best.

Hello Shubhanu,
As per your rank, the preferred colleges for you are Singhad Academy of Engineering & Priyadarshini Bhagwad College of Engineering. However, check here to know more:
https://www.shiksha.com/b-tech/resources/mhcet-college-predictor