GRE

Hi Vedant,
GATE scores are accepted in Germany. However, you should check the entry requirements, you may not even require to take any test other than IELTS and German language proficiency tests.

You should take GRE and IELTS at least two months before the deadline.

Hi,
Some popular ones are mentioned below:
For GRE follow ETS: GRE The Official Guide to the Revised General Test, Kaplan's GRE Premier and Barron's GRE. A number of practice tests are available online. For TOEFL : Official Guide To The TOEFL by ETS, Cambridge Preparation for the TOEFL Test etc. For IELTS The Official Cambridge Guide to IELTS Official IELTS Practice Materials (1 and 2) by British Council
Cambridge ESOL
IDP: IELTS Australia and so on.

Yes, you can prepare for CAT and GMAT together, because mostly, they would be the same. GMAT is for seeking MBA and GRE is for M.S. opportunities.

Some colleges ask for its scorecard, so you may consider giving both the exams.

For masters, you need to apply for GRE but some colleges ask for TOEFL or IELTS score as well.

Purchase GRE book by ETS publisher. It covers all the relevant topics for GRE.

Hi,
Some of the most reputed ones are HEC-Paris, INSEAD, EDHEC, Emlyon, ESCP, etc. You can check the websites for the admission requirements. GRE scores are typically accepted.

Hi, for Master's degree, GRE requirement will depend on the university and the programme. Not every university requires GRE. IELTS or TOEFL is required for English language proficiency. Most important are your academic grades.