Do I have to install drivers after formatting my macbook pro?

For the computer itself no. When Yosemite is installed all your drivers will be installed too. If you have any peripheral devices (printers, scanners, and the like) those may have drivers that your computer will automatically install or you may need to download them and install. For example, when I got my new computer and went to configure my printer the computer downloaded the drivers from Apple and installed it. My scanner didn’t though, I had to go to Epson’s website and download that devices driver.