No, Akeeba backs up the entire site and the database and creates an installer.
After you back up the site you will have an installer with your entire site ready to install, an exact copy of what you have now, Joomla, the template, the contents, etc, which runs similar to a stock install of Joomla or a Rocket Launcher.
there is no need to install Joomla first, nor is there a way to apply an Akeeba back up to an existing install.
Akeeba has several videos on their site, grab a cup of coffee, sit back and watch them.
You'll be ready to go in no time.
For RokQuickCart, you should search or post here for instruction to manually uninstall if you are have trouble.