In terms of performance, there is very little difference between ext2 and ext4. One aspect of performance, is reliability. Having a journaled fs like ext4 provides the "rest of the story".
I would not worry about formatting the drive first. The installer will assist you with taking care of that, and as well as and even better than dban or Gparted or any other tool. "Pre-formatting" the drive will distract from your goal of installing a Linux distro, and could cause additional issues when using the tool that would have to be resolved before your ever get to the actual install.
Have you decided on a distro? To avoid the normal "distro wars" that commence with the question, pick one, install it, run it for a while. You can ALWAYS install a different distro later on.
And finally, the first rule of killing Windows/installing Linux is save any files you want to keep (docs, spreadsheets, movies, books, pictures, etc. to some off machine drive or thumb drive or cloud service. Then dive in and install Linux.