The FastPictureViewer Codec Pack codecs are strictly read-only, there never modify raw files in any way or form.
Microsoft does not "approve" anything, however one of their teams used our product in conjunction with a codec-enabled application they develop (Microsoft Image Composite Editor, a powerful panorama stitcher). They found our codecs to work great and said so in plain English on their web page: the entire quote is “The table below lists several WIC codecs offered by third parties. We have not tested all of these codecs with ICE. In our experience, the FastPictureViewer Codec Pack is much faster at decoding CR2 raw images than the codec provided by Canon, and unlike Canon's codec, it comes with a 64-bit version that will work with the 64-bit version of ICE”, Google should find it easily. Our product is also listed in the Windows 7 software compatibility list, as we indicate on the web page, and we are a Microsoft Registered Partner as well as a Microsoft BizSpark startup company, which means they help us do what we do by providing developement tools and support.
The setup let users op-out any unwanted codec during installation. It is possible to install only what's needed to handle, say, CR2 files and nothing else, however there is no harm in installing the entire package, which is the default option.
The product is delivered as a standard Windows Installer database and is uninstallable from Control Panel.