Princeton

https://www.shiksha.com/tags/princeton-university-tdp-358252
Please check it here.

Hello Ayush,
For a definition please check here:
https://en.wikipedia.org/wiki/Ivy_League
Ivy
Leagues represent excellence, irrespective of the nationality you have to excel in your academics and be an all-rounder. You must have the potential to give back to the society. Apart from these traits, you must take the SAT or ACT to be considered for admissions. I will advice you to check the university websites, go through the admission requirements and mould your profile. Please visit the wiki link above.

You need a CGPA of 4 and higher to apply to ivy leagues. Your overall profile that includes co-curricular, sports, community services, etc. should also be impressive.

Take a sample test on any of the free test sites and check your level. if you need preparation, you may join any of the classes mentioned by you to score high.

Hi, LORs are generally from counselors, teachers, supervisors and managers ( if you are working), it has to be someone who knows your skills and competencies, if the students you are talking about worked with you or are in a position of recommending you, they might but generally its s no.

Hi
The only similarity is that both contain Quantitative aptitude and English but the level of GRE is as per the international standard so it might not give you the same practice. You may try some sample papers of ssc cgl and see.

Hi Sauvik,
It's hard to compare, both TPR and Manhattan are quite popular. One way to find out is by visiting the centers and find out the statistics. Try to get in touch with ex and current students. Compare the study materials and the schedule, most importantly are the instructors certified? Diagnostic tests are important, enquire how realistic are the mock tests with the actual tests. Finally it's upto an individual how he deals with competitive tests no matter what. So choose the center as per your suitability.
Hope this helped. Please feel free to revert for any clarification.