Talking about the Office Update. It's already available in Windows Update, but here is the tricky part, if you are in Windows 8 RT Home screen and you open the Right Side Menu, Settings, there is an option for Windows Update. Unfortunately, that Windows Update does check (it may do it but it does not show them) for the optional updates. The Update to Office 2013 Full Student Version is an Optional Update. To download this Update you should go to the traditional Windows Desktop, open the Right Menu, select Control Panel, System and Security and then Windows Update. There you need to select optional updates and pick the update for Office Preview.
I hope that this trick helps you with this adaptation issue.