Which book should I refer to improve my English and vocabulary for MAT and CMAT preparation?

Candidates can refer to How to Prepare for Logical Reasoning for CAT by Arun Sharma and DI & LR for CAT by Nishit K. Sinha. 

Yes, Caselets are important for CAT DILR. They help develop skills in interpreting data, identifying relationships and solving logical problems.

CAT does not have a fixed number of questions from Caselets. Usually, one Caselet-based set with 4-5 questions may appear in the DILR section.

Candidates can refer to High School English Grammar and Composition by Wren and Martin. CAT previous-year questions, grammar exercises and mock tests are also useful.

Yes, understanding Parts of Speech helps candidates improve grammar, sentence correction, para completion and overall Verbal Ability skills.