Take a look at http://www.asus.com/Notebooks_Ultrabooks/X550CA/HelpDesk_Download/. It appears that they have most of that software if you choose "Windows 8" from the dropdown.
Note that while the dropdown also has a Windows 8.1 section, I think that's only for the software that is different between Windows 8 and Windows 8.1. If you're running Windows 8.1, you'll probably want to use the versions of the software from the Windows 8.1 section for some things.