Do I still need to apply for OPT?

1. The university is beginning the process to petition and apply for my H1B visa. I will graduate in May. Do I still need to apply for OPT?

2. Just in case, if my H1-b visa is approved before the date of my starting work, there will be a period of unemployment. How far the unemployment time will have impact on me?

 

Thank you so much for taking time to help me out!