TOEFL

Hi,
IELTS is more demanding than TOEFL. For Germany, you have to score minimum 6 bands in IELTS. IELTS is excellent option for global education than any other source.

TOEFL doesn't really need any book. It is all about your English listening speaking and writing skills. Try to improve with some English book reference. You need to score 6.0 score or more than that to get accepted in any college abroad.
All the best.

IELTS acceps all over the world, even US midst of the institutions accepting IELTS.
TOEFL is an online exam. IELTS you have to write manually.

ToEFL and IELTS ARE VALID ONLY FOR TWO YEARS. Hence you do it before you plan to go abroad

Hi,
TOEFL is usually accepted in USA and Canada. For Europe, IELTS and CAE are more acceptable. Also, since most of the courses offered are not in English, you might have to consider learning French. Here's a link for the university to help you
https://studyabroad.shiksha.com/france/universities/pierre-and-marie-curie-university

IELTS and TOEFL are language proficiency exams and GRE is competitive exam for Masters in US or Germany.

Yes why not if you can.

Dear Zeeshan, the actual conversion for the CGPA lies with the university & none would have the exact idea. Still you may self check it on the website for WES credential evaluation @ http://www.wes.org/students/igpacalc.asp.

Dear Steffi, 2 years is a pretty long time to study GRE & TOEFL as generally the students take 3 to 6 months to prepare & give the tests.
Since you are doing B.Sc which reflects your interest to pursue your Ms in USA BUT, to remind you that US universities would need a 16 years of education background or a US comparable degree to give you admission for their Ms courses.