Compressed files on an NTFS volume are shown in a blue color. Folders that are partially compressed will have a dark blue color, files and folders that are entirely compressed will show up in a light blue color. For more information on file-based compression see Notes on NTFS.
Yes. To be able to search even complex file types like Microsoft Word, Excel, or PowerPoint, UltraSearch uses the so-called IFilter interface, which is provided by the operating system. Third-party applications can also provide their own treatment routines that can be used to read certain file formats. Many file formats, such as the usual office formats, are already handled by the operating system's own routines.
If you want to search for all files with a certain file extension, use the prefix ext: or extension:, for example:
or just type *.txt
to search for all text files with the extension "txt".