To score good marks in JEE Main it is very important that your concepts are clear and you build strong fundamentals.

HC Verma is one of the most renowned book of physics. It helps you to clear your concepts and you can solve questions for your practice. 

It is not necessary but you should solve it for your practice.

You should also refer to previous year questions to understand the pattern and level of the questions asked in the exam.

All the Best!!