Back in time when I had to install additional Windows Components on a 2003 Server the Windows Comopnents Wizard asked me to insert the install disk or point to a folder which contains the install files. In Windows Server 2008 this was changed and all files were copied to the C:\Windows\WinSxS folder so when I decided to install a feature or a role all files were already on the machine. Unfortunately these files cannot be removed but in Windows Server 2012 you have this option to save space, have smaller server footprint, and even satisfy your security officer: this is called features on demand.
In Windows Server 2012 -just like in the previous version – you can add IIS through the Add roles and features wizard. The GUI navigates you all the steps necessary for the installation and offers you the option to install any additional role service considering dependencies.